The company said it achieved record sales volumes for a first quarter of iron ore and pellets, of 84.3 million tonnes, compared with 77.9Mt in the previous corresponding period.

"Vale SA maintained a strong supply and sales discipline in 1Q18 as part of its commitment to maximise margins over volume," the company said.

Iron ore production was 82Mt for the quarter, some 4.2Mt lower than the first quarter of 2017 and 11.4Mt lower than the fourth quarter.

This was mainly due to the company's 2017 decision to reduce its production of lower grade ore, plus "an intense rain season" in the first quarter.

It said its sales mix was improved by the ramp-up of its S11D operation and its average iron content reached 64.4% in the first quarter - "by far the best among its peers".

Vale reaffirmed its 2018 guidance of 390Mt of iron ore.

Elsewhere, its manganese production was more than 20% lower than in the first quarter of last year, as its Azul mine production fell by more than a third for the period mainly due to lower grades.

Nickel was 17.9% lower after some operations were placed on care and maintenance last year, copper production was down 13.2% as non-competitive mines were shuttered and there was an unscheduled shutdown at the Coleman mine, coal was at a similar level but cobalt production rose 5.4% and gold as a by-product rose by 7.6%.

Shares in the company closed down marginally yesterday to BRL44.54 but remain near a seven-year high reached in February.