UK-listed miner Kaz Minerals reported strong increases in copper and gold production on Thursday.
Kaz said full-year 2017 copper production was up 80% on the prior year at 259 kilotonnes (kt).
Annual gold output was also at the higher end of its forecasts.
However, the shares slid 3.5% on Thursday morning after the production update was released.
Fourth-quarter copper output actually declined over the final three months of the year versus the prior quarter, raising concerns over the outlook.
Copper output in the most recent quarter slid to 65 kt versus 75 kt in the prior period, which Kaz said reflected grade reduction at Aktogay and Bozshakol concentrator maintenance.
Kaz, which is focused on open pit mining in Kazakhstan, also said fourth-quarter zinc in concentrate output was 12 kt, with full-year production of 58 kt, below guidance of 60-70 kt due to delayed access to high grade ore.
Annual output increase
“The performance of our two recently commissioned mines at Bozshakol and Aktogay has delivered an 80% increase in annual copper output into a tightening market and gold production at the top of our guidance range,” said chief executive Andrew Southam.
Copper prices have risen by nearly 20% over the past year, helped by rising demand from China.
Gold has risen by around 12%, helped by US dollar weakness over recent weeks.