SÃO PAULO, Brazil — Brazilian mining company Vale SA has been facing difficulties at two of its nickel operations—Onça Puma in the northern Brazilian state of Pará and its New Caledonia project in the South Pacific.

Onça Puma ceased operations before the end of the second quarter due to breakdowns in two furnaces.

"We are still assessing the extent of the repairs needed and the time required to perform them," Vale said in its second-quarter report. "Initial indications suggest it is likely that both furnaces will be out of operation for the next few months."

At New Caledonia, an incident at an acid plant in May led to the closure of the unit and the company declared force majeure. "We are planning repairs for the acid plant, and all equipment is expected to be operational by year-end," Vale said.

Despite the setbacks, Vale’s total nickel output grew 8.8 percent in the second quarter to 60,900 tonnes from 56,000 tonnes in the same period last year. The company said nickel output could have been higher if it were not for the temporary suspension of the Sudbury Mine in Ontario due to an accident in January.

"The longer-than-expected temporary suspension—for safety assessment of mining operations in Sudbury—negatively affected finished nickel production" in the second quarter, Vale said.

Sudbury and Sorowako in Indonesia accounted for most of the finished nickel production during the second quarter—17,400 tonnes at Sudbury, up 69.1 percent from a year earlier, and 17,000 tonnes at Sorowako, an 11.6-percent decline. Output at Voisey’s Bay in Labrador fell 5.2 percent to about 15,000 tonnes because the unit was affected by maintenance stoppages in Sudbury, where part of the feed is processed. Production at the Thompson Mine in Manitoba totaled about 7,000 tonnes in the second quarter, up 1 percent from a year ago.

Vale said that due to the reduced availability of feed, it had moved up maintenance stoppages slated for the third quarter to the second quarter.