At the same time, Japanese companies are finding it harder than originally hoped to recycle rare earths from electronics and to begin rare earth mining and refining in Vietnam.

Although rare earths are crucial to the supply chains of some of the world’s biggest manufacturers, the industry that mines and refines them has long been characterized by small, entrepreneurial companies. Lately, though, soaring prices have contributed to industry consolidation.

Last month, for example, Solvay, a big Belgian chemical-industrial corporation announced that it would pay $4.8 billion to acquire Rhodia of France, a technological leader in making complex chemicals based on rare earths.

That same day, April 4, Molycorp, the only American company currently producing rare earths, said it had paid $89 million for a more than 90 percent stake in Silmet of Estonia, a much smaller company that is Rhodia’s only European rival in rare earth processing.

In Malaysia, where the giant rare earth refinery is under construction near the eastern port of Kuantan, regulators are delaying approval for an operating permit amid public concern about naturally occurring low-level radioactive contamination of the rare earth ore, which will be mined in Australia.

Raja Dato Abdul Aziz bin Raja Adnan, the director general of the Malaysian Atomic Energy Licensing Board, said the board had asked the Lynas Corporation of Australia, which is building the refinery, to provide additional documentation before accepting its application for an initial operating permit. It will take up to six months to review the application, Raja Adnan said, and Lynas will not be allowed to bring any raw material to the plant until a permit is issued.

But Nicholas Curtis, Lynas’s executive chairman, said that he believed the company could obtain the necessary approvals before September and that his company was sticking to its plan to begin feeding Australian ore into the Malaysian refinery’s kilns by the end of that month.