NIPKB Stroitehnika CJSC (Russia):

Sizikov S. А., General Director, Ph. D. in Technical Sciences, Vyatkin G. М., Deputy General Director on Marketing

Skripilov А. P., Junior Researcher

E-mail (common): stroitehnika@mail.ru

Interstroyproekt (Russia):

Shuloyakov A. D., General Director, Ph. D. in Technical Sciences, interstroyproekt@mail.ru

Stone crushing screenings after their grading become valuable raw material for production of building mortar and concrete. Grading of screenings coarser than 0–5 mm requires preliminary drying, which is expedient to conduct using vibrofluidized bed drying plants. A process of feeding screen ings mass drying and dustremoval by vibropneumatic method in vibrofluidized bed drying plants with a view to remove contaminating finedis persed admixtures (particles finer 0.16 mm), as well as a process of dedusted screenings grading on vibrating screen into two size fractions — 0–0.63 mm and 0.63–5 mm. Drying and dustremoval of screenings in vibrofluidized bed drying plants is performed on troughingoscillating conveyer with double bottom, the upper bottom being a flat nonsifting grate. Material is fed on grate, being transported alongwise it in 100–150 mm layer, owing to grate viberation. Air (hot — in drying, atmospheric — in dustremoval) is fed undergrate and passes through grate and vibrofluidized bed, being sucked from overgrate space by means of exhauster. Vibration regime of vibrofluidized bed drying plants is chosed so as to provide for loadcarrying grate harmonic vibrations vertical acceleration to exceed acceleration of gravity by the factor of 1.5—2.5, in order to maintain vibrotransport of material layer upon grate with continuous «tossing» in every oscillation period of grate. Air blowing rate through vibrofluidized bed is set at the level of particles' hovering velocity, to provide for their removal from processed material. Calculation method, permitting to determine rational parameters of vibrofluidized bed plants, used for drying, dustremoval and vibroscreening of stone crushing screenings, is presented.

1. Chlenov V. A., Mikhaylov N. V. Vibrokipyashchiy sloy (Vibrofluidized bed). Moscow, Nauka, 1972, 341 p.

2. Aerov M. E., Todes O. M. Gidravlicheskiye i teplovyye osnovy raboty apparatov so statsionarnym i kipyashchim zernistym sloyem (Hydraulic and thermal bases of devices with stationary and fluidized granular bed work). Leningrad, Khimiya, 1968, 512 p.