The decline in production was due to unplanned calciner maintenance, the company said on Thursday April 27.

Production in the first nine months of South32’s financial year was down 3% year-on-year to 2,904,000 tonnes, and alumina sales were flat at 2,927,000 tonnes.

South32 holds an 86% stake in Worsley Alumina.

South32’s share of production at Brazil Alumina, in which it holds a 36% stake, fell 7% or 23,000 tonnes quarter-on-quarter to 324,000 tonnes in the January to March period as a result of heavy rainfall.

Sales, in contrast were up 5% quarter-on-quarter to 356,000 tonnes.

Across the Australia and Brazil projects, South32’s alumina production fell 2% year-on-year in the January to March quarter at 1,288,000 tonnes. In the first nine months of the financial year, production also fell 2% to 3,901,000 tonnes of alumina.

South32’s full-year production guidance is unchanged from previous expectations.

Production at Worsley is forecast at 3,965,000 tonnes of alumina in the 12 months to the end of June 2017, roughly flat with the previous year.

Production in Brazil is expected to fall just over 1% year-on-year to 1,320,000 tonnes of alumina.