The invention relates to a process for treating
tail gas of a
rare earth mineral
powder and concentrated sulphuric acid
roasting process. The process comprises the following steps of: introducing the
tail gas of 300 DEG C of the process into a dust remover for dust removal with a
machine; then introducing the
tail gas into a condenser for cooling, condensing massive sulphuric acid
fog and water vapour in the
smoke and recycling acid liquor; introducing the cooled
smoke into an acid
fog collector, collecting acid
fog and water fog in the
smoke for recycling; boosting the treated smoke by a fan, introducing the treated smoke into a first absorber, washing by diluted acid liquor or process water to remove residual sulphuric acid fog,
hydrofluoric acid and fluosilicic acid from the smoke; andthen introducing the smoke into a second absorber, washing the smoke by an alkali washing
tower to remove residual sulphuric acid fog,
hydrofluoric acid and SO2 gas from the smoke, and discharging the smoke out after defogging. The process provided by the invention can save massive smoke cooling water, produce less waste water, reduce waste
water treatment cost, and recycle the
side product fluoric acid produced by
solid mineral substances, sulphuric acid,
hydrofluoric acid and the like in the tail gas as a
raw material for recycling
fluorine.