A mixer , comprising: a housing comprising a fluid inlet , an additive inlet , and an outlet , the housing defining a mixing chamber in fluid communication with the fluid inlet , the additive inlet , and the outlet ; an impeller disposed in the mixing chamber , wherein, when rotated, the impeller draws fluid through the fluid inlet ; a slinger disposed in the mixing chamber and configured to receive the fluid from the impeller and to receive an additive from the additive inlet , wherein, when rotated, the slinger slings the fluid and the additive radially outwards and wherein the impeller and the slinger form a slinger/impeller assembly ; a stator disposed at least partially around the slinger , the stator comprising vanes spaced circumferentially apart so as to define flowpaths therebetween; the slinger and the impeller have inlet faces (134-1, 136-1) and backs (134-2, 136-2) respectively, and wherein the slinger and the impeller are disposed in a back-to-back configuration, such that the impeller drives the fluid radially outward of the slinger , upward in the mixing chamber , and then radially inward toward a middle of the slinger ; characterized in that the stator forms a shearing ring disposed radially around the impeller/slinger assembly , the stator comprising first and second annular portions stacked together, the first annular portion defining a first flowpath area and the second annular portion defining a second flowpath area , wherein the first flowpath area is greater than the second flowpath area and wherein the second annular portion is disposed between the first annular portion and the impeller . a housing comprising a fluid inlet , an additive inlet , and an outlet , the housing defining a mixing chamber in fluid communication with the fluid inlet , the additive inlet , and the outlet ; an impeller disposed in the mixing chamber , wherein, when rotated, the impeller draws fluid through the fluid inlet ; a slinger disposed in the mixing chamber and configured to receive the fluid from the impeller and to receive an additive from the additive inlet , wherein, when rotated, the slinger slings the fluid and the additive radially outwards and wherein the impeller and the slinger form a slinger/impeller assembly ; a stator disposed at least partially around the slinger , the stator comprising vanes spaced circumferentially apart so as to define flowpaths therebetween; the slinger and the impeller have inlet faces (134-1, 136-1) and backs (134-2, 136-2) respectively, and wherein the slinger and the impeller are disposed in a back-to-back configuration, such that the impeller drives the fluid radially outward of the slinger , upward in the mixing chamber , and then radially inward toward a middle of the slinger ; characterized in that the stator forms a shearing ring disposed radially around the impeller/slinger assembly , the stator comprising first and second annular portions stacked together, the first annular portion defining a first flowpath area and the second annular portion defining a second flowpath area , wherein the first flowpath area is greater than the second flowpath area and wherein the second annular portion is disposed between the first annular portion and the impeller . <EOS>