ISSN:
1365-3091
Quelle:
Blackwell Publishing Journal Backfiles 1879-2005
Thema:
Geologie und Paläontologie
Notizen:
Accurate particle-size measurement by sieving requires that consideration is given to particle shape and screen opening size variations. The effect of particle shape has been studied by determining experimentally the probability of passage through each of five woven-wire screens of 35 different mm-sized ellipsoids. These range in shape from T/D= 0.2 to 1.0 and from L/D= 1.125 to 2.625, where T is particle thickness, L is particle length, and D is particle intermediate diameter. Passage tests were performed for both static and dynamic conditions of sieving.A mathematical sieving theory stemming from the idea of particle passing probability is developed. The theory is put to use by computer-simulated sieving of idealized input samples of simple shape make-up. When near-spheres are sieved it is found that a bar-type histogram is a justifiable depiction. For some other more realistic shape inputs, what is obtained are broad, overlapping bell-shaped fraction distributions considerably offset from the nominal openings of the limiting screens. For these distributions, conventional representation in histogram form is incongruous.The treatment presented contains allowance for screen opening size variations. Some apparently polymodal distributions are probably explainable as a result of unsuspected differences between the screens used and an ideal screen series.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1111/j.1365-3091.1968.tb00853.x
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