Abstract: The invention relates to the mixing of a gas with a liquid. The apparatus has a mixing space (5) between two surfaces of revolution one inside the other, into which space the liquid and the gas are fed tangentially so that the mixture comes into a rotary motion into the space. An inner mantle (2) with a conical intermediate section a forms a cross-sectional annular chamber which is smaller than the cross-section of the upper section of the annular chamber section (5). The invention can be used for example, in froth flotation processes, in dissolving processes, or in the aeration of waters.

Abstract: A method and apparatus for grinding granular solids in liquid slurry form within a mill. The solids density of the feed slurry is maintained below the solids density in the mill, thus causing the liquid to flush through the mill, preferentially carrying and discharging finer relative to coarser particles. Discharged solids thus have a smaller concentration of overground solids, and grinding capacity and power consumption by the mill are optimized.