Global mining company Rio Tinto has suffered a major slide in profit in its 2015 interim results, revealing a drop of more than 80 per cent.

The miner released its first-half results today, showing its net earnings of $US4.4 billion last year had tumbled to $US806 million in the same time period this year.

The fall is largely due to the plunging iron ore price as a result of a glut in the market and slowing demand from China.

Rio's half yearly underlying earnings of $US2.9 billion in 2015 were down by 43 per cent compared to last year's figure of $US5.1 billion.

The miner said its global production of 154 million tonnes was 11 per cent higher than in the first half of 2014, following a ramp up in Pilbara production.

The company said it had reduced costs by more than $US500 million and had a net debt of $US13.7 billion.

Rio said it expected to return more than $US6 billion to shareholders this year.

The company said cost reductions, exchange rates and lower energy costs had offset the almost 40 per cent iron ore price decline.

Seeing signs of recovery: Sam Walsh

Rio Tinto's chief executive, Sam Walsh, said these were challenging times for the industry.

Sorry, this video has expired Sam Walsh speaks to The Business

"We've produced a very robust set of numbers despite what continues to be a pretty challenging environment for the mining industry," he said.



"For some time it's been apparent that the economic environment has been adjusting to what is now called 'the new normal'.

"But let's be clear - we'll see continued economic growth from this larger base, including an increase in the long-term demand for all of our commodities."

Mr Walsh suggested that while there was a shift to what he called the "new normal", demand for Rio's commodities should remain strong.

"Since 2008, developed markets in both Europe and USA have been through difficult periods.

"But we do now appear to be seeing signs of recovery.

"And we're starting to sense the potential from emerging market economies including India and Indonesia."

Mr Walsh predicted better times were ahead.

"The economic environment has been challenging particularly for commodities with some prices falling to levels not seen since 2009," he said.

"But this cyclical weakness will pass as the momentum of global economic growth picks up and the commodity markets rebalance."

Rio Tinto, BHP Billiton accused of collusion

Rio Tinto and its rival BHP Billiton were accused of being behind the massive slump in iron ore prices.

Fortescue Metals Group founder Andrew Forrest claimed the two majors flooded the market with iron in a bid to gain more market share by knocking out higher cost producers.

It led the Federal Government to announce it would launch an inquiry into whether the two companies were in collusion, but the Commonwealth later reneged on the move.