REC «Mekhanobr-Tekhnika» (St. Petersburg, Russia):

Gladkova V. V., Senior Engineer, gladkova_vv@npk-mt.spb.ru
Kazakov S. V., Leading Designer, Candidate of Engineering Sciences, kazakov_sv@npk-mt.spb.ru

Saint Petersburg Mining University (St. Petersburg, Russia):
Karapetyan K. G., Associate Professor, Candidate of Chemical Sciences, karapetian@spmi.ru

Perm State University (Perm, Russia):
Otroshchenko A. A., Head of Laboratory, alfa.distress@gmail.com

The study covers various crushing and vibratory classification options for the particularly brittle material apatite glass (phosphate glass), used in agricultural engineering as a prolonged-action fertilizer. The aim of the study is to minimize the yield and recycling requirements for screenings, which should, in turn, ensure energy savings through a reduction of sinter material volumes. Two types of crushers were selected for apatite glass crushing, both capable of ensuring the minimum yield of fine grade particles: a DVG 200×125 roller crusher with smooth rolls and a VKD^® vibratory cone crusher with the crushing cone diameter of 450 mm. The results of comparative tests demonstrated the absolute superiority of the vibratory crushing technology. The yield of the fine fraction of –1.25+0 mm after the VKD-450 crusher amounted to 10.5 % against 29 % when using the roller crusher. The data obtained are in perfect agreement with the results of vibratory crushing of other comparatively brittle materials, for example, synthetic corundum. The structure of the apatite glass grain surface after the roller crusher and the vibratory cone crusher was studied by 3D laser scanning using a Keyence VK-x200 microscope. It has been established that samples after the roller crusher have greater surface roughness as compared to the product of the vibratory cone crusher, with an additional increase in such key parameters as the maximum peak height and the arithmetic average of peak heights. The apatite glass grains obtained after the vibratory cone crusher have a noticeably lower effective viscosity and a lower coefficient of internal friction than the material received from the roller crusher. It has also been shown that vibratory screening of apatite glass should be preferably carried out using steel screens that ensure higher grain-size separation efficiency than polyurethane screens.
The work was carried out with the support of the grant issued by the Russian Science Foundation (project No. 17-79-30056) under the scientific supervision of academician L. A. Vaisberg.

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