Pilbara iron ore shipments for 2018 came in at 338.2 million tonnes, 2% higher than 2017 and at the upper end of guidance.

The average realised price of iron ore sales dropped by 4% to US$62.50 per dry metric tonne.

Guidance for 2019 has been set at 338-350Mt.

The company said the "limited disruption" to Robe Valley lump and fines shipments following a plant fire last week at the Cape Lambert port had been factored into guidance.

Rio's long-stated goal is annual production of 360Mt, and the successful implementation of the AutoHaul autonomous rail system in late December will help bring it closer to that goal, with the rail being the only remaining bottleneck.

The company is now focused on optimising autonomous operations.

The copper production increase was a 33% jump year-on-year to 633,500t to beat guidance.

Guidance for 2019 is 550,000-600,000t, with Kennecott Utah expected to see increased variability in grade.

Bauxite production of 50.4Mt and aluminium production of 3.5Mt were both slightly lower than 2017.

For 2019, Rio expects to produce 56-59Mt of bauxite, 3.2-3.4Mt of aluminium and 8.1-8.4Mt of alumina.

Rio CEO J-S Jacques described the December quarter as a solid operational period.

"During the year, we further strengthened our asset portfolio, continuing to invest in high quality growth," he said.

"2018 saw the early completion of Amrun, the deployment of AutoHaul, the Koodaideri and Robe River investments and the signing of the power agreement at Oyu Tolgoi.

"Meanwhile, we completed disposals of $8.6 billion, including the Grasberg mine in Indonesia and our remaining coal assets.

"With a firm ‘value over volume' focus and disciplined allocation of capital, we will continue to progress our strategic objectives and to deliver superior returns to shareholders in the short, medium and long-term."

The company spent $488 million on exploration in 2018, with 85% incurred by central exploration (greenfields) and the copper & diamonds division.

BMO analyst Edward Sterck said the results were as expected but had forecast higher production for 2019, describing the numbers as "a touch light". 

"On average the midpoints of the new target ranges are 5% lower than our estimates," he said. 

BMO has a London share price target of £43 (US$55.7) per share, compared to the current £39/share level. 

Bernstein's Paul Gait, who saw the results in line with expectations, has the major miner at £50/share. 

*Kristie Batten is editor of www.miningnews.net