The problem of intensification of the grinding process in ejector jet mills is considered. The results of experimental studies of the ejector and the materials grinding process in these mills with a blow to the barrier are presented. It is shown that the density of the two-phase flow is determined by the pressure in the initial section of the acceleration tube. To increase the density of the two-phase flow, a jet mill with an external pressure supply is proposed. Comparative tests of an ejector jet mill and an ejector mill with external pressure supply have shown that an increase in the density of the two-phase flow allows simultaneously increasing the grinding degree and the consumption concentration of the material with the same flow rate of compressed air in the acceleration tube. Thus, productivity increases and specific energy costs are reduced when grinding materials in ejector jet mills.