An injector, specially for flotation cells, has a supply pipe (1) for the suspension which is joined by an orifice plate (3) to a vertical mixer pipe (2). Its outflow (8) carries a radial diffuser (6). An air supply ring (9) furnishes the air intake to the slots (4) in the pipe. Reduction valves (12) permit a control of the air intake. The orifice plate (3) has 3 to 8 round holes as orifices, uniformly distributed. The mixing tube has a diameter (D) of min. 16cm (20cm); its length (b) should be 2.5 D-4D.
