Abstract: An apparatus for determining the particle size distribution and for characterizing the particle shapes of a particle mixture has a metering device for classifying a particle mixture supplied in a particle stream to the apparatus. An optoelectronic measurement section is provided that has a light source and an image collecting device aligned with one another, wherein the particle stream is guided between the light source and the image collecting device. The image collecting device has a plurality of electrooptical image recording units directed onto the particle stream and having different image recording scales matched to one another to cover the whole measurement range of the apparatus. A computing unit converts digital image points recorded by the recording units into a size determination of the particles.

Abstract: In a screening machine with a three-dimensional oscillating screening movement and a control unit for converting a given vibration level into the required energy supply for the electromagnet, the results of screening analyses are to be reproducible or comparable; to this end it is provided that the control unit (26) is designed for calculating the machine acceleration as a function of the respective determined vibration level and the simultaneously determined frequency value as a control value for the energy supply to the electromagnet and for the setpoint-actual value comparison of the calculated machine acceleration actual value with a given machine acceleration setpoint value and for compensating a determined machine acceleration deviation by adjusting the energy supply to the electromagnet (21) on the basis of the change in the vibration level calculated as a function of the given frequency.

Abstract: A centrifugal mill exchangeable cassette for laboratory use has a base body a drive motor, including a drive shaft, connected to the base body. A housing with cover enclosing the base body and the drive motor is provided. The housing has a milling chamber. The cover has an inlet opening for feeding materials to be milled to the milling chamber. A rotor is connected to the drive shaft of the drive motor. The rotor is positioned in the milling chamber. An exchangeable cassette with an annular receptacle and with a radially inner wall consisting of an annular sieve and connected to the annular receptacle is provided. The exchangeable cassette is positioned in the housing so as to surround the milling chamber and the rotor for catching the material milled by the rotor in the milling chamber. The exchangeable cassette has a detachable lid covering the milling chamber and the rotor.

Abstract: In a screening machine with a three-dimensional screening motion, a screen carrier for at least one screen plate is provided. The screen carrier is movable relative to a housing from which it is supported by springs. The screen carrier is driven by an electromagnetic drive device. The amplitude of oscillation of the screen carrier should be accurately readable, on the one hand, and, on the other hand, made adjustable for comparative tests. For this purpose, between the housing and the screen carrier an inductive displacement pickup for determining the amplitude of oscillation of the screen carrier is provided. This pickup is connected to a control unit which represents the determined amplitude of oscillation on an optical display and/or controls the electromagnet drive device to obtain a predetermined amplitude of oscillation.

Abstract: An apparatus for fine grinding of, in particular, material samples for laboratory experiments. The apparatus has a fixed grinding member and a rotating grinding member, which are disposed in such a way that each has a surface facing the other and slightly spaced therefrom, with the material which is to be ground being received and passed between these surfaces. The problem faced by such an apparatus is that samples have to be introduced and discharged one by one, so that the work is carried out as a batch process. It is also difficult to accurately adjust the grinding degree. In order to solve these problems, and to carry out a continuous grinding of hard and very hard materials, as well as to be able to adjust the grain size of the grinding, the invention proposal is that the grinding members on the one hand be a fixed cylindrical body and on the other hand be a roller body which rotates coaxially therein.