A flotation cell for treating particles suspended in slurry and for separating the slurry into underflow and overflow , the flotation cell comprising a flotation tank comprising a centre , a perimeter , a bottom , and a side wall ; and a launder and a launder lip surrounding the perimeter of the flotation tank; wherein the flotation tank further comprises blast tubes for introducing slurry infeed into the flotation tank, a blast tube comprising an inlet nozzle for feeding slurry infeed into the blast tube, an inlet for pressurized gas, the slurry infeed subjected to the pressurized gas as it is discharged from the inlet nozzle, an elongated chamber arranged to receive under pressure the slurry infeed, an outlet nozzle configured to restrict flow of slurry infeed from the outlet nozzle, and to maintain slurry infeed in the elongated chamber under pressure, and to produce a supersonic shockwave into the slurry infeed , the supersonic shockwave inducing formation of flotation gas bubble - particle agglomerates, and an impinger configured to contact a flow of slurry infeed from the outlet nozzle and to direct the flow of slurry infeed radially outwards and upwards of the impinger, characterized in that the underflow is arranged to be removed from the lower part of the flotation tank , and at or near the side wall via a tailings outlet arranged at the side wall of the flotation tank, and a height (H) of the flotation tank, measured as the distance from the bottom to the launder lip , at the perimeter of the flotation tank is at most 20 % lower than the height (H) at the centre of the flotation tank for providing a settling zone deeper near the side wall of the flotation tank. a flotation tank comprising a centre , a perimeter , a bottom , and a side wall ; and a launder and a launder lip surrounding the perimeter of the flotation tank; wherein the flotation tank further comprises blast tubes for introducing slurry infeed into the flotation tank, a blast tube comprising an inlet nozzle for feeding slurry infeed into the blast tube, an inlet for pressurized gas, the slurry infeed subjected to the pressurized gas as it is discharged from the inlet nozzle, an elongated chamber arranged to receive under pressure the slurry infeed, an outlet nozzle configured to restrict flow of slurry infeed from the outlet nozzle, and to maintain slurry infeed in the elongated chamber under pressure, and to produce a supersonic shockwave into the slurry infeed , the supersonic shockwave inducing formation of flotation gas bubble - particle agglomerates, and an impinger configured to contact a flow of slurry infeed from the outlet nozzle and to direct the flow of slurry infeed radially outwards and upwards of the impinger, characterized in that the underflow is arranged to be removed from the lower part of the flotation tank , and at or near the side wall via a tailings outlet arranged at the side wall of the flotation tank, and a height (H) of the flotation tank, measured as the distance from the bottom to the launder lip , at the perimeter of the flotation tank is at most 20 % lower than the height (H) at the centre of the flotation tank for providing a settling zone deeper near the side wall of the flotation tank. <EOS>