Chile's seven copper smelters produced 96,600 mt of copper in May, down 20.9% from the same month of 2016, according to data from the Chilean Copper Commission.
Production of electrolytic cathode, produced by refining anodes produced by the smelters, slipped 4.9% in May to 71,700 mt.
Copper output during the first five months of the year was likewise down at 534,600 mt, 18.3% lower than a year earlier, the data showed. Production of electrolytic cathodes fell 16.6% to 343,000 mt in the same period.
Four of Chile's smelters are operated by state mining company Codelco, which said Monday that cumulative output fell at three -- Chuquicamata, Caletones and Potrerillos -- while rising at its fourth smelter, Ventanas.
Production at Chuquicamatra, Caletones and Potrerillos was hit by maintenance shutdowns and bad weather, as well as problems with acid plants, the company said.
Codelco added that the drop in smelter production would not affect the company's total copper production this year, as it sold more copper as concentrates rather than cathode.
Mine production of copper in Chile reached 2.077 million mt during the first five months of the year, according to commission data, down 9.7% year on year, reflecting the impact of a crippling 44-day strike by workers at BHP Billiton-operated Escondida mine last February and March.
