Method and apparatus for floating classification

The invention relates to a method and device for cleaning contaminated solid-liquid mixtures. The invention relates in particular to a method and a device for removing unwanted matter and impurities from an aqueous paper fiber suspension by flotation. The device comprises: at least one first conduit (2) for supplying a liquid; at least one second conduit (3) for supplying a solid-liquid mixture; at least one third conduit (4)， which connects the first to the second conduit (2， 3); at least one venturi mixing element (5)， said venturi mixing element (5) having two cones (7， 10) facing each other， the small through-opening (12， 13) of each cone opening into a cavity-defining chamber (9)， and the region of the opening into the chamber (9) being designed in such a way that eachsmall through-opening (12， 13) of the cones continues in a non-conical conduit section (8， 11) which corresponds to the cross-sectional area of the small through-openings (12，13)， said non-conical conduit sections (8， 11) leading to the chamber (9) between the cones， the large through-opening of the first cone (7) being connected to the first conduit (2) via the third conduit (4) and the large through-opening of the second cone (10) being connected to the second conduit (3) via the third conduit (4)， and the small through-opening (12) of the first cone (7) being smaller than the small through-opening (13) of the second cone (10) and the two cones (7，10) facing each other and the non-conical conduit sections (8， 11) being arranged along the longitudinal axis relative each other; a fourth conduit (6) for carrying a gas， preferably air， said fourth conduit (6) opening into the chamber (9) of the venturi mixing element (5); and at least one fractionator for separating the foam caused by the flotation and being mounted downstream of the second conduit (3). The invention relates to a method and device for cleaning contaminated solid-liquid mixtures. The invention relates in particular to a method and a device for removing unwanted matter and impurities from an aqueous paper fiber suspension by flotation. The device comprises: at least one first conduit (2) for supplying a liquid; at least one second conduit (3) for supplying a solid-liquid mixture; at least one third conduit (4)， which connects the first to the second conduit (2， 3); at least one venturi mixing element (5)， said venturi mixing element (5) having two cones (7， 10) facing each other， the small through-opening (12， 13) of each cone opening into a cavity-defining chamber (9)， and the region of the opening into the chamber (9) being designed in such a way that eachsmall through-opening (12， 13) of the cones continues in a non-conical conduit section (8， 11) which corresponds to the cross-sectional area of the small through-openings (12，13)， said non-conical conduit sections (8， 11) leading to the chamber (9) between the cones， the large through-opening of the first cone (7) being connected to the first conduit (2) via the third conduit (4) and the large through-opening of the second cone (10) being connected to the second conduit (3) via the third conduit (4)， and the small through-opening (12) of the first cone (7) being smaller than the small through-opening (13) of the second cone (10) and the two cones (7，10) facing each other and the non-conical conduit sections (8， 11) being arranged along the longitudinal axis relative each other; a fourth conduit (6) for carrying a gas， preferably air， said fourth conduit (6) opening into the chamber (9) of the venturi mixing element (5); and at least one fractionator for separating the foam caused by the flotation and being mounted downstream of the second conduit (3).