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Grinding Aids and Transport in Comminution.
For Reference Only At Bureau Libraries :51 pages
This report presents an investigation of particulate transport and grinding kinetics in ball mills, and the results were analyzed in terms of phenomenological and/or analytical models. First, the effect of liner design and configuration on material transport through tumbling mills was studied. A laboratory-scale comparison of transport in drums and mills fitted with angular square lifters (asl) was made with drums and mills fitted with conventional bar lifters. The holdup of material in the asl drum at any feed rate was less in the forward-spiraling than in the reverse-spiraling operation, whereas the peclet (pe) number was found to be independent of the spiraling direction. The conventional bar mill showed a slight difference in holdup but pe is essentially the same for the two types of mills. Second, the role of polymeric chemical additives in improving mill performance was studied. Published data on fine particle production in wet grinding were analyzed as a function of the specific energy consumed by the mill with and without grinding aids. Polymeric grinding aids probably increase the mill productivity by permitting operation at higher solid-liquid ratios, but there is no energy saving. Preliminary experimental results showed that at high solid-liquid ratios, the high slurry viscosity in the mill causes the balls to stick to the mill shell and thereby tend to act as a flywheel that consumes less energy.
CP; Final Contract Report;
For Reference Only At Bureau Libraries
Univ. of Utah
Page last reviewed: November 12, 2021
Content source: National Institute for Occupational Safety and Health Education and Information Division