Big miners will spend hundreds of millions of dollars on embryonic low-carbon metal trials in Western Australia after BHP, Rio Tinto and BlueScope agreed to develop the country’s largest iron-making electric smelting furnace.

The low-emissions iron facility will be constructed next door to BHP’s shuttered nickel refinery in Kwinana after the Cook government lured the project away from Port Kembla in NSW for $75 million.