(Sharecast News) - Mining giant Rio Tinto said it was starting to see a "step-change" in production with output of iron ore, bauxite and aluminium all growing in the second quarter, though iron ore shipments were worse than expected due to a train derailment during the period.

Iron ore shipments from the company's projects in the Pilbara region of Western Australia totalled 80.3m tonnes during the three months to 30 June, up 3% on the first quarter but short of the 82.1Mt consensus forecast.

The company said that both production and shipments were impacted by a train collision in mid-May, which resulted in around six days of lost rail capacity and full stockpiles at some mines. Pilbara iron ore production rose just 2% quarter-on-quarter to 79.5m tonnes.

Elsewhere, bauxite production increased 10% over the three-month period to 14.7Mt, while mined copper production rose 10% to 171,000kt. Aluminium output was flat at 824kt, while titanium dioxide slag fell 6% to 238kt and iron ore pellets and concentrate output in Canada dropped 16% to 2.2Mt.

"Our operational performance continues to progress," said Rio chief executive Jakob Stausholm. "While there are still significant improvements ahead, we are beginning to see a step-change in production, including from our Queensland bauxite business following the roll-out of the Safe Production System."

Shares were down 1.4% at 5,120p in early deals on Tuesday.