Abstract: A vacuum-spraying grinder in which material to be ground is sprayed by centrifugal force onto an impact surface, comprising a fixed chamber connected to a suction device and housing a target having an annular inwardly directed impact surface with a vertical axis of symmetry of revolution. A rotor is located in the chamber coaxially with the impact surface of the target, and comprises an upper part located at the level of the target in the form of a horizontal disc provided with radial channels communicating with a central feed orifice in the upper part of the disc, and a lower part in the form of a vertical shaft.

Abstract: A feeding and discharging apparatus for continuously feeding particulate material to and continuously discharging material from a chamber formed of a machine at subatmospheric pressure, e.g. a vacuum jet mill. The apparatus employs a feeding device for feeding particulate material, a discharging device for discharging particulate material, at least two feeding chambers, each having an inlet connected to the feeding device and an outlet for connection to said chamber. A valve structure is provided for closing the feeding chambers. At least two discharging chambers are provided each having an inlet for connection to the chamber formed of the machine and an outlet connected to said discharging device, a valve assembly is provided for closing the discharging chambers, each of the feeding and discharging chambers comprising a compartment for storing the material, and a pressurizing structure for producing a subatmospheric pressure in each compartment.