After missing so many deadlines and going billions over budget, the first line of Citic Pacific's massive Sino Iron project in Australia has finally gone into production.

Platts reports initial production of 4 million tonnes could be followed by five more lines for a total production of 24 million tonnes per year from the Pilbara magnetite resource of 2 billion tonnes.

Sino Iron, which is one of the biggest foreign investments ever made by a Chinese firm, is almost four years behind schedule thanks to operational and technical difficulties. The mine has already cost Hong Kong-listed Citic $8 billion to develop and the final bill could reach $10 billion.

Back in 2006 when the project first came off the drawing board, it was forecast by its high-profile backers, which includes the China Development Bank, to cost under $2 billion.

Sino Iron, one of a number of overseas Chinese iron ore ventures, was designed to wrest some of the pricing power away from BHP Billiton, Rio Tinto and Vale which control some 60% of the 1.1 billion seaborne iron ore trade.

The spot price of 62% iron ore imported into the port city Tianjin in northern China on Monday was $131.40 a tonne.

The price of the commodity has slid more than 9% since the start of the year, but has held up relatively well against predictions of decline as global supply ramps up.