To provide a flotation separator by which a convection current of a treating liquid does not arise even when rising speed of gas blown into a treating tank of a selectiveflotation apparatus becomes fast and contact efficiency between materials to be subjected to selectiveflotation and the blown gas is improved. 浮選装置の処理槽内に吹き込んだ気体の上昇速度が速くなったとしても処理液の対流が生じず、しかも、浮選する対象物と吹き込んだ気体との間の接触効率の向上した浮遊分離装置を提供する。 - 特許庁