Device (100,200) for processing a substance, its oxide and/or its sulphide, the substance being a metal or metalloid, the device (100,200) comprising a reaction chamber (110,210) and an expansion chamber (120,220); a plasma generator device (160,260), arranged to emit a plasma stream (163,263) into the reaction chamber (110,210), the plasma stream (163,263) comprising said material; a gas provision means (170), arranged to provide an inert (171) and/or reducing (172) gas to the reaction chamber (110,210); a DeLaval nozzle (180,280), arranged to convey gases from the reaction chamber (110,210) to the expansion chamber (120,220) and arranged to lower the temperature of the gases passing through the DeLaval nozzle (180,280) to below the condensation temperature of the substance, causing the gas compound to condense into a liquid or solid phase; and a vessel (190,290), into which the condensed substance is directed by the DeLaval nozzle (180,280). The invention also relates to a method.