PERTH (miningweekly.com) – Diversified major Rio Tinto has reported a 57-million-tonne increase in the ore reserve estimate at its Pilbara iron-ore assets in 2016.

The miner on Friday reported that iron-ore reserves for 2016 stood at 3.51-billion tonnes, compared with the 3.45-billion tonnes estimated in 2015.

The company told shareholders that the increase in the estimated iron-ore reserve resulted from the ongoing resource development drilling programme designed to maintain ore reserve coverage ahead of mining depletion rates.

At its Canadian iron-ore assets, Rio reported that mineral resources decreased by 674-million tonnes in 2016, from 2.76-billion tonnes to just over 2-billion tonnes.

The change followed both technical and financial reassessment of the mineral resource and did not impact the ore reserves, Rio said.

The current life-of-mine plan for the Canadian iron-ore assets anticipated production life extending to 2042, based on the reported ore reserves only.

Meanwhile, a 19-million-tonne increase in the mineral resource at Rio’s Jadar lithium and borates project, in Serbia, was also reported, with the project now estimated to host some 136-million tonnes.

The Jadar mineral resource includes an indicated resource of 52.4-million tonnes at 1.79% lithium oxide and an inferred resource of 83.3-million tonnes, at 1.9% lithium oxide.

At the Argyle diamond mine, the estimated mineral resource, exclusive of ore reserves, decreased by 29-million tonnes to 15-million tonnes.

Rio noted that the previously reported mineral resource included mineralisation that could support a potential extension of the currently planned mine life.

However, as mine-life extension options are under review, the reported mineral resource has now been restricted to those parts of the mineralisation which can potentially be developed, mined and processed during the mine life defined by the current underground operation.

Rio told shareholders that, as the change to the Argyle mineral resource had no impact on the reported ore reserves, the reduction had no bearing on the current mine plan, which will see production continue until 2021.