Abstract: Apparatus for classifying particulate material on a particle by particle basis according to the extent to which the particles possess certain attributes, such as the presence of particular colors when viewed from different directions. A particle feeder (12) feeds particles past an inspection system (13) which inspects each particle and derives signals which are a measure of a plurality of attributes of the particle. A separation or airblast mechanism (14) operates to direct particles to multiple outlets (15) according to the signals derived by the inspection system (13). This operation is controlled by a signal processor which can store a plurality of sets of specific values of attributes each set of which is typical of one of a plurality of particular classes into which the particulate material is to be classified and can compare subsequently measured sets of values of attributes of successive particles with the stored sets to determine a closest match with one of the particular classes.

Abstract: Particles are fed for sorting by a radial distributor having an upper surface on which the particles gradually spread arcuately and are displaced radially outwardly, by for example vibration of the distributor, to a lip of the upper surface where they define one or more curved arrays as the fall over the lip. As they fall in free flight trajectory paths the particles present a curved array one particle deep to a separating device arranged to sort the particles according to the degree they possess a particular characteristic.

Abstract: Selection means is provided for particles following a free flight trajectory path, those particles having a preselected characteristic, such as fluorescence under x-ray bombardment, being detected and a signal being transmitted on such detection to electrostatic charging means to locally ionize the atmosphere and thereby charge the detected particle as it passes through the locally ionized atmosphere, the charged particle being deflected from its free flight trajectory path by an electric field. Non-detected and uncharged particles continue in the free flight trajectory path. Particles may be detected in a path having lateral spread by providing detecting means and electrostatic charging means which are together responsive to particles in respective portions of the path.

Abstract: Method and apparatus for sorting objects according to the degree to which they possess a required characteristic. Objects are moved in a line on a conveyor belt past a line of detectors each responsive to the required characteristic. Each detector produces a time sequence of output signals and the signals from successive detectors are accumulated. The objects are projected from the downstream end of the conveyor belt in a free flight path past an optical scanner and a series of air blast nozzles. The scanner determines the portions and sizes of the objects and objects selected on a comparison of the detector signals and signals from the scanner are blasted with air jets from appropriate nozzles so as to be deflected from their free flight trajectory. Deflected and undeflected objects are caught in separate collection bins.