UK-Australian mining firm Rio Tinto expects production from its new Simandou mine in Guinea to lift its overall iron ore grades in the coming years, while the ramp-up of fellow resources firm BHP's Samarco mine in Brazil could produce similar results.
Rio Tinto's average realised iron ore grade fell to a decade low of about 60.5pc this year, data from its 2025 Capital Markets Day presentation show. But the company expects the high-grade Simandou mine in Guinea to increase its average product ore grades to around 61.7pc by 2032.
The company downgraded the specification of its Pilbara Blend fines ore from 61.6pc Fe to 60.8pc Fe in May. It also increased its sales of lower-grade SP10 ore, which has lower iron and higher impurity levels, over 2024.
BHP is in a similar situation to Rio Tinto. The company's typical Australian ore grades have declined over recent years, dropping below 62pc Fe. But increased production at the higher-grade Samarco operations in 2025 likely supported its overall ore grades.
BHP has not announced any longer-term ore grade forecasts. But a planned increase in its Samarco production, which it expects to average 67pc Fe in the current financial year, is likely to boost grades.
Simandou
Rio Tinto opened Simandou in November and shipped its first load of ore in early December. It will increase production at the site to 60mn t/yr — equivalent to about 18pc of its 2024 Western Australian ore output — by 2028.
The company expects to sell 5mn-10mn t of high-grade ore from the mine in 2026, before ramping up production to 60mn t/yr by 2028.
Simandou will account for about 15pc of Rio Tinto's total output at that stage, with production from the company's increasingly mid-grade Pilbara mines and Canadian plants accounting for the rest.
Samarco
BHP aims to produce 7mn-7.5mn t of 67pc Fe ore pellets at Samarco during the 2025-2026 financial year to 30 June, before ramping up capacity to 30mn t/yr by 2028.
The company's entire equity-basis production growth in July-September came from Samarco. It produced 2.1mn t of ore over the quarter, up from 1.3mn t a year earlier.
The Samarco ramp-up should lift BHP's average iron ore grade over the next few years, despite the Pilbara grade declines.
Samarco will also diversify BHP's customer base. Close to 90pc of its major Australian iron ore shipments went to China in 2024, estimates from marine tracking platform Kpler show, making it vulnerable to economic and policy changes in the country.
But Samarco's 2024 sales were split between the Middle East and Africa, Asia, Europe, and the Americas. A third of the mine's customers were in the Americas, with another quarter in Africa and the Middle East, according to Samarco's 2024 financial statement.
Grade gains
BHP and Rio Tinto offset grade declines at their Pilbara mines in 2025 by selling more lump and fewer fines. This has helped the companies maintain stable realised prices despite falling iron ore grades.
But this trend is being driven by what are potentially temporary demand-side factors. Chinese steelmakers began to favour lower-grade lump this year because of concerns about sintering restrictions.
This is not guaranteed to continue. Instead, Rio Tinto and BHP's overseas mines could provide a more stable path to offsetting grade declines than increasing lump sales, given uncertainty over demand.
