Mining giant BHP Billiton says iron ore prices are unlikely to eclipse $US100 a tonne again, with expectations of steel consumption growth in China slowing further next year.

"I've learnt never to say never and there's always short-term variations, but I think that if you use basic economics … certainly $100 seems high," BHP's president of iron ore Jimmy Wilson told reporters in Shanghai on Thursday.

"It's hard to see that significant bump [in demand] that we've seen coming from China happen again."

BHP's senior management group, including chief executive Andrew Mackenzie, was in Shanghai to celebrate the shipping of its one billionth tonne of iron ore to China.

The first shipment departed from Port Hedland in 1973.

"It took nearly 30 years for BHP Billiton to ship 100 million tonnes of iron ore to China and then only 12 more years to reach the one billion tonne milestone," Mr Mackenzie said.

The milestone was testament to China's extraordinary rate of development, he said. At current rates the next 1 billion tonnes milestone would take just five years to reach.

But though imports into China have surged, prices have nearly halved, dropping under $US70 a tonne for the first time in five years.

The drop comes amid a supply glut brought on by aggressive expansion by major miners Rio Tinto, BHP and Vale – even as Chinese economic growth cools.

Iron ore prices rallied briefly last month after China cut interest rates for the first time since 2012, but have since failed to stem the rout.

Analysts are tipping further downward pressure on iron ore prices.

BHP said annual Chinese steel production growth was likely to remain at around 3 per cent for the next decade but a slowdown in consumption was now anticipated.

"Consumption growth is about 1.5 percent this year and slowing to between 0.5-1.5 percent next year - we see modest to marginal steel consumption growth," said Alan Chirgwin, general manager for marketing and iron ore.

Mike Henry, BHP's president of marketing, said he expected China's economic growth rate to come in at around 7.2 or 7.3 per cent, which would confirm analyst expectations of the slowest rate of growth since 1990.

He said the GDP growth rate would continue to slow to around 7 per cent and then toward 6 per cent in the coming 10 or 15 years.

"We're not predicting a sharp curtailment of exports but if it does happen … steel demand will still be there elsewhere," Mr Henry said. "We're here today to celebrate the relationship with China and the business here but ultimately we're selling to global markets."

BHP, a significant coal producer, said it had not been greatly affected China's decision to reintroduce import tariffs.

Those tariffs will be removed after a bilateral free trade agreement between Australia and China comes into force.

"We continue to ship every tonne of coal that we produce, so there hasn't been any impact," Mr Henry said, adding that a recent rise in Chinese domestic prices had negated the impact of the tariffs.

Meanwhile, China's leaders have emphasised the need for its economy to adapt to a "new normal" of slower but higher-quality economic growth.

The phrase featured prominently in a statement issued after a key three-day economic policy meeting of senior leaders and officials concluded on Thursday.

But the statement stopped short of setting an economic growth target for next year, which is usually made public in March.

At the meeting, the leaders including President Xi Jinping and Premier Li Keqiang stressed that the economy still faced "relatively big" downward pressures such as increasing difficulties for businesses and the emergence of economic risks.

"Chinese authorities will likely tolerate a slower growth rate at around 7 per cent under the framework of 'new normal' economy and will strike a balance between social, environmental, and economic targets," said ANZ chief Greater China economist Liu Li-Gang.