Premier Mill The vacuum model of the company’s ring mill is a submersible unit used for convenient batch processing of dispersible formulations. It allows for the sub-surface addition of free-flowing additives into the process vessel, which simplifies handling and eliminates dusting. A separate premix disperser is not required. Powders are quickly incorporated into the process vehicle by the twin dispersion impellers and ground by the proprietary submersible milling chamber. The mill allows users to add pigment or filler materials in a closed, sub-surface manner, predisperse the solids and complete the milling operation in a single process vessel.