Chemical and Metallurgical Institute named after Zh. Abishev (Karaganda, Republic of Kazakhstan):

Malyshev V. P., Head of Laboratory, Doctor of Engineering Sciences, Professor
Makasheva A. M., Chief Researcher, Doctor of Engineering Sciences, Professor
Zubrina Yu. S., Junior Researcher
E-mail (common): eia_hmi@mail.ru

A comparative analysis of grinding process in ball and rod mills was performed on the basis of the probabilistic model of grinding. The analysis showed that rod mills are preferred for grinding of coarser size fractions. The reason for this is their advantage with respect to steric (spatial-orientation) factor. With respect to rod grinding, this factor is greater than that of ball grinding in total size range of grains, owing to smaller shielding effect by rod for grains, rather than that provided by ball. Activation (disintegration) factor of rod grinding also exceeds that of ball grinding, although somewhat to a smaller degree, but very strongly with respect to coarse size fractions. Combined effect of steric and activation factors leads to formation of maximums in the range of mm size fractions. This maximum is significantly higher with respect to rod grinding, than for ball grinding. For this reason, coarse size fractions rod grinding process theoretically is much more efficient, than that of ball grinding, which in practical operation results in lower electric power consumption. The calculations showed, that with rod grinding, distribution of size fractions becomes more uniform, which is also in good agreement with the practical operation data. With rod grinding, just as with ball grinding, logarithmically normal distribution is formed in the course of grinding process, which is related to applicability of integrated model of grinding to any variants of sequential disintegration of material. The obtained probabilistic model of rod grinding, taking into account all acting factors, may be considered most complete and ready for practical application.

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