China says it is curbing exports to redress the environmental damage done by decades of mining, but has also made clear it would prefer to be the biggest consumer of rare earths rather than the biggest producer.

China's appetite is growing fast as it seeks to maintain its stranglehold over the group of 17 elements used in new technologies like smartphones and hybrid cars.

A concerted effort to build an entire industrial chain means that China, which produces more than 90 percent of world supplies of rare earths, is now consuming 65 percent of output versus 25 percent a decade ago.

"By 2014 or 2015, China will probably be in a net import situation for certain rare earths," said Mark Smith, chief executive of Colorado-based miner Molycorp, which this year acquired China-based Neo Material Technologies to boost its processing know-how and its presence in China.

"When the demand is there, that's where the supply has to go. Over 80 percent of the magnets produced in the world come from China and that is growing just tremendously every year," Smith told Reuters in an interview.

While its tight export controls have sparked disputes with the United States, Japan and Europe, Beijing's priorities extend beyond controlling supplies and prices. It aims to dominate downstream products like magnets, which can be made smaller and more powerful with rare earths.

China's coking coal sector offers a lesson, analysts say. Determined to feed its own steel mills instead of shipping the material abroad, China changed itself from the world's biggest exporter into one of the biggest importers.

SHARING THE BURDEN

The United States Geological Survey says China has about half of global rare earth reserves, with 55 million tonnes, as compared to Russia with 19 million and the United States with 13 million. But China says the figure is closer to a quarter and churning out 90 percent of world supplies is unsustainable.

Domestic consumption will grow at least 10 percent a year in the next few years, said Li Zhong, vice-president of China's biggest miner, Baotou Rare Earth, and with Beijing also capping output, the growth can only be met by a further export cut or increased imports.

Beijing's policies have already pushed up prices, persuading countries like the United States, Canada and India to resume production after shutting mines decades ago. Processing is also becoming attractive, with Australia's Lynas Corp seeking approval to build a plant in Malaysia.

HIGH-TECH REWARDS

For Beijing, shipping low-end ore abroad meant it paid all the environmental costs but gained none of the rewards from high-tech manufacturing. Its efforts to clean up mining and limit foreign sales are part of the same strategy to maximize returns from its resources.

"The control over global rare earth output is important as far as it buys China the time needed to establish the supply chain," said Jane Nakano, a researcher at the Center for Strategic and International Studies in Washington.

As part of the push downstream, big producing regions like Baotou in Inner Mongolia are being encouraged to emulate the likes of Japan's Hitachi, which began as a copper mine and turned itself into multi-billion dollar high-tech conglomerate.

One key industry is magnets, used in renewable energy, satellites, MRIs and gas drilling. Chinese producers like Zhenghai Magnetic Materials contribute more than 80 percent of global output, up from almost zero two decades ago.

China also makes more than 70 percent of the world's total luminescent materials, hydrogen storage cells and glass polishing materials, the industry ministry said in a report last month. All these items utilize rare earths.

While the ministry said China still lagged in downstream technologies, export curbs are playing a role in the effort to catch up, encouraging foreign firms to bring technology to China in pursuit of cheaper rare earth.

"We were supplying all the glass plants and they were a huge operation in the United States for over 100 years, but those operations have essentially all moved to China," said Michael Silver, chief executive of advanced materials maker American Elements, which gets rare earths from China.

Glass makers were lured to China because of cerium, used in glass coloring and polishing. Neodymium is also used in energy-saving light bulbs, whose production has also moved to China.

IMPORTS

China's experience with coking coal provides a precedent.

As the world's biggest producer of the steelmaking material, China was also a massive exporter, shipping millions of tonnes a year to Europe and Japan.

But it wanted more. It imposed export curbs, rode out trade disputes and became a net importer by 2008 following a massive expansion of its steel sector. Imports now meet a fifth of China's 550 million-tonne annual consumption.

While China is unlikely to import light rare earths such as lanthanum and cerium, abundant in Inner Mongolia, shortages of heavy and medium rare earths could arise.

"Given the way demand is increasing, it is quite possible China will eventually be importing some heavy rare earth elements," said an official with a rare earth magnet producer.

Smith of Molycorp hopes for a time when his company will not only fill gaps in global supplies but also supply China itself.

"Simply put, we don't think China can keep up with the demand for rare earths," he said. "They are going to have to go to the outside."

(Editing by Clarence Fernandez)

By David Stanway