1,058,914. Froth flotation. OUTOKUMPU OY. June 14, 1965, No. 25097/65. Heading B2H. Froth flotation apparatus operating undermon head ofprises a pre conditioning and aerating unit 1, into which pulp and gas are introduced via pipes 3, 4, the pulp being fed via a pipe 6 into a flotation chamber 8. Additional gas is introduced via a pipe 13.