The device for evaporating a treatment liquid comprises a cylindrical enclosure having an outlet orifice opening out into the top end of the enclosure, the enclosure being placed vertically and having a heated inside wall, and liquid nozzles associated with a blow pipe for blowing air under pressure so as to form a jet comprising a mixture of air and of pulverized treatment liquid in a direction that is tangential to the inside wall of the enclosure, each liquid nozzle and the associated blow pipe being arranged so that the jet of mixture is formed in an upper portion of the enclosure and is downwardly inclined.