EXPERIMENTAL RESEARCH OF A MULTISTAGE GRAVITATIONAL CLASSIFIER

Аннотация

The classification of polydisperse materials is widely used in many industries. Of the wide range of
classification equipment, the most promising are multistage gravitational classifiers. The classification process in
multistage gravitational classifiers is quite complicated and requires the necessary experimental research to ensure
the given efficiency. To receive reliable information allowing to obtain the most effective recommendations for their
structure and use, a set of experimental research was carried out. The research results showed that multistage
classifiers of small sizes provide a consistently high quality of separation, however their performance, for an
apparatus with a cross section of 80x80 mm no more than 100 kg/h, is insignificant, as a result of which they cannot
be used for most production processes. Classifiers with higher performance must have significant sizes. It is
advisable to use multistage shelf classifiers with boundary separation sizes of 0.5-2 mm. With a boundary size of less
than 0.5 mm, a steady decrease in the separation efficiency is observed, and with a boundary size of the order of
0.05-0.1 mm, the classification efficiency decreases sharply. With an increase in the boundary separation grain of
more than 2 mm, a decrease in the classification efficiency is also observed (figure 1). The experiments to determine
the separation efficiency in the modernized and conventional structures of classifiers in the separation of quartz sand
with particle sizes of 0-2 mm relative to the boundary separation size of гр = 1 mm showed the following. The
mutual arrangement of the efficiency curves shows that an increase in the separation efficiency for the modernized
classifier is up to 10% when the optimum, providing the highest quality separation, air velocity per section of the
apparatus is achieved. Similar results were obtained for other materials (sylvinite, meal, gypsum) for various
boundary separation sizes (from 0.5 to 2 mm). In general, the separation efficiency in the modernized structure of the
shelf classifier for various materials was 5-10% higher than in a conventional one. The experimental research of the
modernized classifier structure showed that the proposed structural additions, ceteris paribus, contribute to a more
uniform distribution of material over the working volume of the apparatus, which, of course, leads to an increase in
the quality of separation.