THEORY OF PROCESSES | |
ArticleName | Ores grinding theory development on the basis of molecular approaches |
ArticleAuthor | Malyshev V. P., Turdukozhaeva А. М., Kaykenov D. А. |
ArticleAuthorData | Chemical and Metallurgical Institute named after Zh. Abishev (Republic of Kazakhstan): Malyshev V. P., Head of Laboratory, eia_hmi@mail.ru Turdukozhaeva A. M., Chief Researcher, eia_hmi@mail.ru
Karaganda State University named after A. E. Buketov (Republic of Kazakhstan): Kaykenov D. A., Researcher |
Abstract | Ore grinding in a ball mill in tumbling regime of random collisions between grinding bodies and ground particles (metal balls and material grains) is likened to kinetics of bimolecular successive irreversible reactions with unlimited number of stages. In both cases the process rate obeys the probabilities of random successive events in mutual presence of interacting bodies in any point of reaction space (concentration factor), collision of one body with another (steric or geometric factor), disintegration in collision (activation factor) and to frequency of collisions. The latter is set by mill's rotation velocity, concentration factor — by volume ratio of balls and ore material loads, steric by balls and grains size ratio with determination of «dead» spaces in collisions, activation — by resultant reaction from impact energy and heat energy, on the one hand, and grain crystal lattice disintegration energy — on the other hand. With that, ball mill grinding results, that were earlier not sufficiently clear, are explained: low energy-efficiency of process, «non-grindability» of fine size fractions, manifestation of double maximums in grain size distribution in initial process stage, this size distribution tending to logarithmic-normal distribution law in final grinding stage, preferred use of large and small balls mix, actual correspondence of optimal balls and grains loads to their equal volume fractions, negligible effect of temperature on process rate. In consequence of mathematical rigor of expression for grains successive disintegration rate, with consideration of each size fraction content accumulation and diminution, a model has been developed, permitting direct calculation of each size fraction yield at any moment of time with total yield of all size fractions being equal to unit. An example of such calculation for quartz ore uniformsize fraction grinding is presented. |
keywords | Grinding, molecular theory, collision, kinetics, ball mill, mechanical energy, heat energy, steric factor |
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Language of full-text | russian |
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