Industry data showed that iron ore delivery costs from Brazil to China were around $22.6 a ton compared to $9 a ton from Australian miners.

To cut freight overheads, Vale launched its big ship plan in 2008. Using Valemax cargo vessels, the company aimed to transport 400,000 tons on each super carrier to China at competitive prices.

But in 2011 a dispute broke out between Chinese ship owners over the super cargo carrier plan after they complained about being kept away from transporting iron ore from Brazil.

The Chinese government reacted by banning Vale's super carriers before imposing restrictions on them docking at the country's ports in 2011.

A breakthrough came when Vale agreed to sell four large iron-ore carriers to Cosco in 2014 and four cargo carriers to China Merchants this year.

The deal involving Cosco was worth about $445 million, but no figures were released for the China Merchants sale.

Even so, there are plans for Cosco and China Merchants to build 10 super cargo carriers to transport Vale's iron ore from Brazil to China.

"We are very confident about the merits of having Valemax (super cargo carriers) between Brazil and China," Ferreira said.

To cater for these large iron ore cargo vessels, China's Ministry of Transport and National Development and Reform Commission announced earlier this month that four ports would be opened up to the 400,000-ton carriers.

"These vessels are more efficient," Ferreira said. "They can reduce costs and at the same time bring down emission levels by 35 percent."

Vale sells more than 150 million tons of iron ore to China annually without revealing further detailed financial figures.

Although the economic slowdown has hit steel demand in the country, Ferreira is still confident about the future.

"Vale believes that despite of the slowdown, China will remain the world's economic engine," he said. "There will be significant opportunities for our industry in the long-term."

Ferreira is also optimistic that Vale can increase its market share in the second-largest economy in the world.

"We are confident we can make inroads in that direction," he said. "We are hopeful we can increase our market share in China from our current 25 percent."

Quality will be the key to Vale's expansion plans here.

"China is demanding higher quality materials to cut down on pollution and increase productivity," Ferreira said.

"Vale has the best quality products in the world with the highest content of iron and the lowest impurities. This helps productivity, cuts down on fuel consumption, which in turn reduces emissions and pollution," he added.

According to figures released by Mysteel, China will import 978 million tons of iron ore this year. Prices will range from $50 to $65 a ton due to oversupply in the market.

"It is hard to predict iron ore prices now," Wei, the analyst, said. "The market has gone through a turbulent time."