An apparatus and method for dispersing solids into a liquid. The solids may be any particulate material, ranging from cohesive to free flowing. The apparatus and method use an auger to deliver the solids from a hopper to a mixer, where the solids are dispersed into one or more liquids. Typically a vacuum is created in the mixer, or other differential pressures may occur between the hopper and mixer. The apparatus and method provide a delivery rate of the solids which is substantially controlled by the auger rotational speed and substantially independent of the vacuum or other differential pressure at certain auger rotational speeds.