Rare earth metals are key to global efforts to switch to cleaner energy -- from batteries in hybrid cars to magnets in wind turbines. Mining and processing the metals causes environmental damage that China, the biggest producer, is no longer willing to bear. China’s rare earth industry each year produces more than five times the amount of waste gas, including deadly fluorine and sulfur dioxide, than the total flared annually by all miners and oil refiners in the U.S...With China now shutting down unregulated rare earth mines and slashing exports, users from Toyota Motor Corp. to Vestas Wind Systems...are concerned that supplies may be constrained...Mining companies including Lynas Corp. from Australia and Molycorp Inc. in the U.S. plan to make up the supply shortfall...[also refers to Baotou Steel Group (Baogang), Unocal]