Rio Tinto (ASX:RIO) has delivered a step-change first-half result, with its Queensland bauxite and alumina operations forming a core link in its aluminium business.

The global miner reported underlying earnings before interest, tax, depreciation and amortisation of $14.8 billion for the half, up 28 per cent.

Profit after tax rose 47 per cent to $6.7 billion, and the company declared an interim dividend of $3.4 billion, up 43 per cent.

Main Image: Rio Tinto’s Amrun project on Cape York Peninsula

Chief executive Simon Trott said the result reflected a combination of factors.

“We achieved a step-change in performance in the first half, which, alongside favourable commodity prices, delivered a 28 per cent increase in underlying EBITDA and a 75 per cent rise in free cash flow.”

Rio Tinto’s aluminium and lithium division lifted underlying EBITDA 38 per cent to $3.3 billion, helped by higher aluminium prices the company said in a report to the ASX.

In Queensland, the company mines bauxite at Weipa and Amrun, on the Gulf of Carpentaria coast of western Cape York Peninsula.

Group bauxite production eased 7 per cent to 28.5 million tonnes for the half, after wet-season weather disrupted Weipa early in the year.

Related: Rio Tinto focus on stronger, sharper direction

Output recovered strongly in the second quarter, and the company expected to claw back about half of the weather-related shortfall over the year.

Rio Tinto continued to progress the Kangwinan project, a proposed new mine and port expansion at its Weipa Southern operations.

The project would add up to 20 million tonnes of annual bauxite capacity, with a final investment decision targeted around the end of 2026.

Named by the Wik Waya Traditional Owners, Kangwinan would largely replace tonnes lost as the Gove and Andoom mines near the end of their lives.

At Gladstone, Rio Tinto operates the Yarwun refinery and holds a majority stake in Queensland Alumina Limited, helping lift group alumina output 8 per cent.

Rio Tinto also struck a landmark partnership with the Queensland and Commonwealth governments in March to safeguard the Boyne aluminium smelter at Gladstone.

The A$2 billion funding package, spread over 10 years, could extend the smelter’s operations to at least 2040.