China’s CMOC Group boosted its cobalt output by more than 170% in 2023, with surging production at a new mine in the Democratic Republic of Congo helping the company leapfrog Glencore Plc as the world’s top producer of the key battery metal.

Hong Kong-listed CMOC produced 55,526 tons of cobalt in 2023, it said in a January 4 filing. In October, Glencore forecast output of as much as 42,000 tons. While investors and traders had been expecting a large increase at CMOC’s massive Kisanfu mine — which came online in the second quarter — the full-year result exceeded the company’s own production guidance by more than 20%.

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Soaring output at the $1.8 billion Kisanfu mine helped trigger a sharp slump in cobalt prices last year, alongside rising production in Indonesia and a rebound in exports from CMOC’s other operation in Congo, Tenke-Fungurume. The market was already in one of its biggest-ever surpluses as 2023 began, and the additional output helped drive a 30% slump in prices over the year.

The mismatch between supply and demand became so acute that by mid-year Glencore had started to stockpile surplus tonnages at its operations in Congo in a bid to bring the market back into balance. Glencore is set to announce its full-production results in February.

CMOC’s copper output also jumped by 51% to 419,539 tons, establishing it as one of the world’s top producers at a time when many miners are struggling to boost output.