PERTH (miningweekly.com) – Wet weather conditions forced a 6% decline in diversified major Rio Tinto’s Pilbara iron-ore production during the first quarter ended March, while production of all other commodities increased or remained steady.

Rio on Tuesday reported that global iron-ore production for the quarter reached 74.7-million tonnes, down 6% on the previous quarter, but up 12% on the previous corresponding period.

The Pilbara operations produced 71.1-million tonnes of ore during the quarter, with Rio’s share being 57.3-million tonnes. While down on the previous quarter, Pilbara production was up 12% on the previous corresponding period following the commissioning of the Nammuldi wet plant and the ramp-up of the Hope Downs 4 project.

Copper production for the first quarter increased by 12% on the fourth quarter of 2014, but declined by 9% on the previous corresponding period, with Rio producing 144 100 t.

The miner noted that the higher copper output was driven by higher throughput from the Kennecott and Escondida operations, while lower grades at the Kennecott mine were responsible for the 9% decline, comparable to the first quarter of 2014.

Hard coking coal production soared by 22% during the quarter, compared with the fourth quarter of 2014, and by 10%, compared with the previous corresponding period, with production levels measured at just over two-million tonnes.

The production of semi-soft coal was up by 23% to the previous quarter, reaching 898 000 t, while thermal coal production remained steady at 4.7-million tonnes.

Rio reported that the higher first-quarter coal production was primarily driven by improved production rates from the Kestrel South mine, following the ramp-up of the longwall, as well as increased semi-soft production at the Mount Thorley and Warkworth mine, and higher thermal production from the Hail Creek mine.

“We continue to drive efficiency in all aspects of our business, which is reflected in our solid production performance during the first quarter,” said Rio CEO Sam Walsh.

“By making the best use of our high-quality assets, low cost base and operating and commercial capability, our aim is to protect our margins in the face of declining prices and maximise returns for shareholders throughout the cycle.”