--- Updates with more detail, broker comment, latest share price ---
Rio Tinto PLC (LON:RIO) produced and shipped more iron ore in the first quarter, despite lower commodity prices, and forecast a similar rise this year.
Rio produced 84mt of ore and shipped 81mt, up 13% and 11% respectively against the same period a year ago.
But that was down 4% and 12% respectively against the fourth quarter last year, with the fall in shipments due to bad weather and exhausted stockpiles.
It said the year-on-year rise in shipments was due to the completion of some brownfield developments and expanded plant in Australia’s Pilbara in 2015.
Production from the Pilbara is now expected to be between 330mt and 340mt in 2017 against 350mt beforehand, subject to final productivity and capital spending plans.
The global miner kept its 2016/17 guidance for ore shipments from Australia and Canada unchanged at about 350 million tonnes (mt).
Broker Liberum Capital said that would mean Rio would have to boost its quarterly sales rate by 9mt for each of the next three quarters, equating to an annual rate of 36mt.
"Happy to remain short miners in the face of this expected ramp-up in supply, not only from Rio, but also from the other majors," the broker said in a note.
The shares rose 19.5p to 2288p.
Mike van Dulken at Accendo Markets said: "The positive share price response today comes from reiterated 2016 guidance despite problems with an automated train system, a continued oil price rebound post-Doha helping commodity sentiment in general and dovish Fed commentary pushing the commodity currency US dollar lower.
"Perversely, the supply disruption that held back Q1 production is serving to shore up commodity prices which rebounded strongly in Q1 from depressed lows on hopes that the worst of the global supply glut might be behind us, with a knock on for share prices."
Big miners have courted controversy for maintaining or increasing production at the same time as commodity prices drop, hitting smaller rivals.
They have rode the storm by slashing costs and improving efficiency, but have also cut or suspended dividend payments.
Rio's bauxite production of 11.1mt improved 6% versus the first quarter of 2015.
Alumina production increased 7%, while aluminium production rose 10% following the successful completion of the ramp-up at the Kitimat smelter.
The group said its expected share of production of bauxite, alumina and aluminium in 2016/17 remains unchanged at 45mt, 7.8mt and 3.6mt, respectively.
Mined copper production was 27% higher, with superior grades at Kennecott, improved throughput and water availability at Escondida and a share of production from Grasberg.
In 2016, Rio expects its share of mined copper production to remain unchanged at between 575 and 625 thousand tonnes (tt).
Refined copper production is also set to be flat at an expected 220-250tt.
During the quarter, the group completed the divestment of the Bengalla coal mine and the restructuring of the Coal & Allied group and said it was selling the Mount Pleasant coal project.
Chief executive Sam Walsh said "These results demonstrate our commitment to operational excellence in 2016, with notable improvements in several important areas, including a strong performance in aluminium.
“However, we continue to experience volatility in commodity prices across all markets.
“In the face of a testing external environment, our focus remains on further cost and productivity improvements, disciplined capital management and maximising free cash flow.”