A little-known cobalt miner in the Democratic Republic of Congo plans to ramp up output so fast it will soon be out-produced only by industry leader Glencore Plc.

Chemaf Sarl, a closely held Lubumbashi-based company, and several other firms are capitalizing on a boom in demand that’s transforming small copper miners into major cobalt players, as refiners and automakers scramble to secure long-term supplies. Prices for the metal, used to make rechargeable batteries in electric vehicles, have more than tripled in the past two years.

New output from Congo means the supply of cobalt could exceed demand for a few years, as it did narrowly in 2017, Guildford, U.K.-based metals trader Darton Commodities Ltd. said in a February report. This surplus will become a deficit when an expected surge in electric-vehicle sales kicks in after 2020 because no new “meaningful” cobalt assets are expected to enter production in that period, according to Darton.

Chemaf is building a processing plant at its Mutoshi mine in Lualaba province that will open in September 2019 and six months later be capable of producing 20,000 metric tons of cobalt a year, Chairman Shiraz Virji said by email. Added to output from its existing Etoile mine, which was about 5,000 tons last year, that could make Chemaf the world’s second-largest producer.