Heavy equipment firms get into gear

"They have increased the ore car's load capacity from 50 cubic meters to 55 cu m based on Rio Tinto's request, which helped us to do our job more efficiently."

The company even won Rio Tinto's award as best supplier in emerging markets in 2013.

"The cooperation with Rio Tinto since 2004 has provided great opportunities for Chinese heavy duty equipment manufacturing companies like us to expand business overseas," said a statement on QRRS' official website.

QRRS is also a supplier for BHP, to which it sold 2,500 custom-built ore cars. Each car can carry 40 tons .

Besides mining equipment makers, Jiangsu-based Yangzhou Tonglee Reefer Container Co Ltd, a subsidiary of China International Marine Containers Group, is providing modular accommodation in many Pilbara mining camps.

Australian miners live in facilities built by Chinese companies, drive mining trucks made in China and deliver iron ore in rail cars from Chinese makers.

That iron ore eventually ends up in China's steel mills.

According to Rio Tinto, the company purchased more than $5 billion worth of goods and services from China for use in its operations worldwide over the past four years.

BHP also has a long-term partnership with Chinese suppliers. It set up a China procurement team based in Shanghai in 2007. And in the past six years, BHP has purchased products worth $4 billion in China.

BHP's Chief Executive Andrew Mackenzie said that through China's strength in steelmaking and manufacturing, part of the iron ore that is exported to China comes back to Australia in the form of high-quality infrastructure and equipment.

"In the past six years, we spent around $4 billion buying capital goods and consumables from China to run our business in Australia," he said.

BHP works with more than 50 suppliers and service providers. In addition to ore cars and modular accommodation, BHP purchases steel fabrication from Tianjin-based Bohai Oil Marine Engineering and Supply Co Ltd for use at its Jimblebar mine in the Pilbara region.

The Chinese steelmaker won a contract valued at $55 million with BHP in 2011. Since then, the company has been growing as an international supplier of steel structure modules.

"The project has definitely assisted us in our overseas expansion," said Peng Wencheng, president of Bohai Oil.

Li Xinchuang, deputy secretary-general of the China Iron and Steel Association, said the mining giants' increasing procurement in China reflects their commitment to the market, which makes them look better than pure sellers.

Wei Zengmin, an analyst at consultancy Mysteel, said that as China's manufacturing ability improves, mining companies will definitely increase procurement in China.