The Separation of Grain by Projection

.1 tlcvice is describetl ~vhich effects a continuous separatior~ of intcrnally infestetl wllcat from sound shea at, and ~11ic11 separates ~vheat into a number of fractions of different test weight. A stream of wheat, projected into still air by rapidly moving belts, is dispersed by the conlbined effects of air drag and gravitation into numerous fractions which are caught in a series of hoppers. Infested kernels fall short of sound grain and are thus separated. Test weight varics progressively and characteristically with distance from the point of projection. Kecently, extensive studies have shown that the principal source 01 microscopic insect Iragrnents in milled products is internal inl'estation (6). The removal of external insects from grain constitutes no particular problem in commercial cleaning. The milling process has been modified to reduce insect fragments in milled products about as far as presently appears ecorlomically feasible (4), and separation of internally infested grain from sound grain would be extremely desirable. At the present time there is no device in use by grain processors which effects this separation (6). The present report deals with the development and application 01 an apparatus which eliminates internally infested kernels from a stream ot grain and which separates grain into fractions of increasing test weight on a contiriuous and rapid basis. General Considerations Grain cleaners in current use grade primarily by behavior in air currents and by length and width of the kernels. Insects develop within kernels of all sizes and shapes and do not affect these dimensions. An intact infested kernel may be differentiated from a sound one of the same size and shape by mass differences (lo), by differences in transparency to X-rays (B), by staining of the egg plug (5, 7), and by the sounds generated bv an internal insect (1). The apparatus here described is designed to take advantage of the lrlass changes induced in a wheat kernel as the insect develops. A stream ol kernels moving with uniform speed is projected into still IManuscript received January 11, 1954. Contribution No. 246, Department of Flour and Feed Milling Industries, and No. 46, Department of Physics, Kansas State College, Manhattan. This research was supported by a grant from the Millers' National Federation, Chicago, Illinois. 2 Department of Physics. 3 Departmrnt of Flour and Feed Milling Industries. 316 Published in CEREAL CHEMISTRY 31:4 (July 1954), pp. 316-325. Published by The American Association of Cereal Chemists.