Research and Engineering Corporation «Mekhanobr-Tekhnika» (Saint-Petersburg, Russia):

Gerasimov A. M., Senior Researcher, Сandidate of Engineering Sciences, gerasimov_am@mtspb.com
Grigoryev I. V., Chief Designer
Ustinov I. D., Head of the Scientific and Educational Center, Doctor of Chemical Sciences, ustinov_id@mtspb.com

In the mining and metallurgical, construction and chemical industries, granular materials represent heterogeneous systems consisting of a solid phase, that may be homogeneous or inhomogeneous in its material composition, with the particle size of less than 5 mm, in contact with a gas phase, which is mainly atmospheric air. Granular materials are most widely used in the mining and metallurgical industry for dry vibrational size classification, agglomeration, and fluidized bed roasting. Dry combined processes of magnetic and electric separation, in which granular raw materials are brought into a state of vibrational fluidization, are taking on great importance in mineral processing. There are different views on how to experimentally estimate the angle of repose. Despite the seeming simplicity of the problem, there are still no standardized or generally accepted methods or devices for measuring the angle. In the overwhelming majority of cases, when the material is freely poured onto a solid horizontal plane, a body with the slope shape approaching a parabola gradually turning into a straight line is formed instead of an ideal cone. This body may even have no straight sections at all. It has been shown that a correct measurement of the slope angle is possible in devices with a retaining wall and an unloading platform. In the device designed, a rectilinear surface is formed for almost all samples of granular (bulk) materials studied, which allows unambiguously establishing their respective angles of repose using non-contact electronic angular gages.
The study was carried out under grant No. 17-79-30056 issued by the Russian Science Foundation.

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