Method of operating a flotation cell, wherein a dispersed fluid mixture is created by feeding at least one gaseous and at least one liquid fluid into a dispersion apparatus , each at a particular volume flow rate (FV, GV), to form gas bubbles from the at least one gaseous fluid that are dispersed in the at least one liquid fluid, wherein a particular gas bubble size of the gas bubbles formed from the gaseous fluid is established by virtue of a particular volume flow ratio between the gaseous fluid and the liquid fluid, wherein the ratio of the respective flow rates relating to the gaseous and liquid fluids is used as controlled variable or manipulated variable for specific closed-loop or open-loop control, wherein the volume flow rate (GV) of the gaseous fluid is greater than the volume flow rate (FV) of the liquid fluid, and the volume flow rate (FV) of the liquid fluid is within a range between 1% and 80%, especially within a range between 5% and 50%, of the volume flow rate (GV) of the gaseous fluid, and wherein the method is performed using the dispersion apparatus , said dispersion apparatus comprising: - a feed device having at least two separate feed units , each set up to supply a fluid with a particular volume flow rate, - a mixing device which is downstream of the feed device and is set up to mix the fluids fed into the feed device , and - a distributor device which is downstream of the mixing device and has at least one exit opening for exit of the fluids mixed in the mixing device from the dispersion apparatus , - wherein the mixing device comprises at least one elongated, especially frustoconical, mixing body that bounds a mixing space, wherein the cross-sectional area of the mixing space increases from the end facing the feed device to the end facing the distributor device . wherein the ratio of the respective flow rates relating to the gaseous and liquid fluids is used as controlled variable or manipulated variable for specific closed-loop or open-loop control, wherein the volume flow rate (GV) of the gaseous fluid is greater than the volume flow rate (FV) of the liquid fluid, and the volume flow rate (FV) of the liquid fluid is within a range between 1% and 80%, especially within a range between 5% and 50%, of the volume flow rate (GV) of the gaseous fluid, and wherein the method is performed using the dispersion apparatus , said dispersion apparatus comprising: - a feed device having at least two separate feed units , each set up to supply a fluid with a particular volume flow rate, - a mixing device which is downstream of the feed device and is set up to mix the fluids fed into the feed device , and - a distributor device which is downstream of the mixing device and has at least one exit opening for exit of the fluids mixed in the mixing device from the dispersion apparatus , - wherein the mixing device comprises at least one elongated, especially frustoconical, mixing body that bounds a mixing space, wherein the cross-sectional area of the mixing space increases from the end facing the feed device to the end facing the distributor device . - a feed device having at least two separate feed units , each set up to supply a fluid with a particular volume flow rate, - a mixing device which is downstream of the feed device and is set up to mix the fluids fed into the feed device , and - a distributor device which is downstream of the mixing device and has at least one exit opening for exit of the fluids mixed in the mixing device from the dispersion apparatus , - wherein the mixing device comprises at least one elongated, especially frustoconical, mixing body that bounds a mixing space, wherein the cross-sectional area of the mixing space increases from the end facing the feed device to the end facing the distributor device . <EOS>