Giant mining equipment has stripped away the palm trees and other vegetation from a jungle bluff here with a Malay name that translates to “Iron Hill.” Huge power shovels gouge long furrows down cliffs of fuchsia clay, scooping out the shiny black iron ore at their base.

The mine here operates round the clock, seven days a week. The Chinese-controlled CAA Resources, which reopened the dormant mine early this year, has rapidly ramped up production to an annual rate of 500,000 tons, with plans to double it by next year.

Its ambitions, though, are being undermined by the shifting global terrain: Iron ore sells for less and less these days.

“China still needs a lot of steel for infrastructure, housing projects and rails,” Li Yang, CAA’s chairman and chief executive, yelled as ore-processing machinery clanked noisily nearby. “The only problem is the pricing.”

With seemingly insatiable demand from China, the price of iron ore, along with many other commodities, soared for most of the past decade. China manufactures half the world’s steel, which is made from iron and used for housing construction, rail lines, carmaking and more.

The boom helped support the rapid growth of companies like CAA, as well as the economies of developing countries rich with resources. From Indonesia and Australia to Peru and Brazil, multinationals and Chinese companies embarked on large-scale, long-term investments in mines.

But the dynamics have changed — and the current downturn may reflect a new reality. China’s economy, once growing in the double digits, has slowed to around 7 percent, with industrial output dropping even more dramatically. Many commodity companies, though, have ramped up production to meet that earlier pace of demand.

The result is a double blow to natural resources companies and emerging markets, with few sectors hurt more than iron ore. Prices are down 48 percent since the start of the year, to $70 a metric ton, a five-year low.

Even in the face of falling prices, producers show no signs of easing off, with low-cost industry giants leading the charge.

Vale of Brazil said in August that it wants to double shipments to China in five years. BHP Billiton of Australia announced plans the same month to invest $2 billion in mine expansion projects. Rio Tinto, a company based in London with extensive operations in Australia, is in the process of bolstering production 13 percent by next year and another 8 percent by 2017.

Chinese companies, too, have been relentlessly expanding overseas. In Malaysia, the number of iron ore mines in operation has increased more than sevenfold since 2007, mainly from Chinese investment.

As iron ore demand has fallen, mines like the one here in Bukit Besi have kept running partly by digging deep into the most iron-rich part of their seams, instead of developing them more evenly, mining the poor-quality ore with the good. That has kept a torrent of iron ore entering the market even as prices have plummeted. “They exacerbate the problem by everyone doing the most profitable part,” said Bruce Diesen, a commodities specialist at Carnegie ASA, an Oslo-based asset management company.

CAA Resources has been at the center of the push here, reopening Malaysia’s most famous mine. Discovered in the jungles of eastern Peninsular Malaysia in 1916 by a Japanese geologist, Bukit Besi became one of the world’s largest mines as it supplied the Japanese steel industry through World War II.

The British seized the mine as war spoils after Japan’s surrender and handed it over to a British company. The British mining company initially struggled with Communist insurgency attacks on its rail lines, including bombings that destroyed three train stations, but nonetheless became a big supplier of ore for Japan’s postwar industrial revival.

Then, in 1971, the mine closed because of what a historic marker here describes as bureaucracy and labor union troubles. The site sat idle for most of the next four decades.

Learning from the mistakes of his predecessors, Mr. Li, the 27-year-old CAA chief and scion of a Chinese family that had grown wealthy in the mainland iron ore industry, immediately worked to build ties with local and national political leaders, as well as with Malaysian royalty.

“If you’ve got these two to support you, then you can do anything you want, because the natural resources are all controlled by them,” Mr. Li said.

Mr. Li, who owns 56 percent of CAA, said that he had paid for each of the ruling party politicians with indirect stakes in the mine to receive the royally granted title of “dato,” which roughly translates as “the honorable.” It costs about $100,000 to arrange each royal grant, he said.

Although anti-corruption groups have campaigned against such arrangements, particularly indirect stakes, Mr. Li said he was simply following common practices in Malaysia. A government-linked industry group in Beijing announced plans on Oct. 24 to introduce standards for Chinese companies in areas like labor rights, environmental protection and community relations.

To avoid potential labor issues, Mr. Li has largely imported workers, who are not unionized. CAA Resources brought in about 40 mining engineers, accountants and other professionals from China, and filled the rest of its work force with laborers from low-wage countries like Cambodia, Myanmar and Vietnam. The workers are on 12-hour shifts, up to seven days a week, and are paid based mostly on how much iron ore each shift can produce, Mr. Li said.

Pacing across the jungle mine, Mr. Li described his recruitment pitch to potential hires. “You can save a lot of money, there is nothing to do here,” he said, “I say, ‘Each of you will be a hero, you will take back 100 percent of your savings, your wife will be happier, your children will be happier.' ”

He has avoided filing an environmental-impact statement by erecting an eight-foot-high, blue corrugated-steel fence across the middle of the site with a gate, and calling it two mines, each less than 500 acres. Only mines over 500 acres require environmental approval.

Now, CAA’s biggest challenges are from outside forces.

For one, Bukit Besi’s ore is less rich in iron than what rivals produce in Australia or Brazil, although better than most Chinese ore. Less concentrated iron ore needs to go through a costly extra step, known as beneficiation, before it can be sold. That eats into CAA’s profit.

Transportation, too, is a costly proposition. Australian and Brazilian iron ore mines are connected by rail lines to deepwater ports that can handle some of the world’s largest bulk freighters. That limits their shipping costs to China at around $8 a ton. By contrast, it costs $16 a ton to ship Malaysian iron ore to China because Malaysian ports are shallower — although a deeper port is scheduled to open by the end of next year.

But CAA benefits from a home-field advantage of sorts.

The Chinese steel industry — and the Chinese government, which guides purchasing policies — has been reluctant to rely exclusively on Australia and Brazil, given its past difficulties. In the years before the global financial crisis, such players sharply increased ore export prices.

“There is a strategic imperative — China does not want to be solely dependent on Australia and Brazil,” said Tim Huxley, chief executive of Wah Kwong Maritime Transport Holdings, a big Hong Kong shipping company active in carrying iron ore to China. “They’ve done that before, and it cost them a lot of money.”

With migrant workers, CAA’s labor costs are tiny compared with those of mines elsewhere. The company has brought in Chinese mining equipment at less than half the cost of American or Japanese equipment — and has the connections with manufacturers to get broken parts fixed quickly.

So Mr. Li insists that his company’s Malaysian mines could still cover their costs and show a modest profit shipping ore back to China at prices close to $80 a ton.

“We’re still positive by this time,” he said. “The open pit process has low costs.”