The year has started with “several challenges” for diversified mining group Rio Tinto’s iron-ore business, resulting in the major downgrading its guidance for 2019.

Pilbara shipments are now expected to be between 333-million and 343-million tonnes for the year, compared with the previous guidance of between 338-million and 350-million tonnes.

The company’s first-quarter Pilbara shipments were 14% lower at 69.1-million tonnes, as weather disruptions in March and a fire at Cape Lambert A in January weighed on its performance.

Cyclone Veronica disrupted ports used by miners Rio and BHP in late March. The company previously warned that 2019's output would be about 14-million tonnes below the previous estimates.

Rio Tinto said in its first-quarter production results announcement on Tuesday that the weather events would also have an impact on the second-quarter’s performance.

Pilbara iron-ore production fell by 9% year-on-year to 76-million tonnes in the quarter under review.

“Our iron-ore business faced several challenges at the start of this year, particularly from tropical cyclones. As a result, and following the continuing assessment of damage at the port resulting from the cyclones and other minor disruptions, 2019 guidance for Pilbara shipments is reduced . . . ,” said CEO Jean-Sébastien Jacques.

The group’s quarterly operational performance in its other divisions was solid and generally higher than last year, he added.

Compared with the first quarter of 2018, copper production increased by 3% to 143 900 t, with strong contributions from the Oyu Tolgoi mine, in Mongolia, and Rio Tinto Kennecott, in the US.

Aluminium production remained stable at 796-million tonnes and bauxite output increased by 1% to 12.76-million tonnes. The bauxite production increased despite several weather events throughout the quarter, which impacted on production at the Amrun, Weipa and Gove mines. Commissioning of the Amrun bauxite mine was completed in March.

Titanium dioxide slag production of 296 000 t was 1% higher than the first quarter of 2018.

First-quarter production at Iron Ore Company of Canada was 5% higher than the corresponding quarter of 2018, despite adverse weather conditions impacting production in February.

“Our focus remains on safety, delivering our ‘value over volume’ strategy and allocating capital with discipline, to continue delivering superior returns to our shareholders in the short, medium and long term,” said Jacques.