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Practical guidelines for predicting the proper conditions of high-energy mixing in a planetary ball mill towards powder flow improvement

Leś Karolina M., Opaliński Ireneusz

Chemical and Process Engineering

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2022

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Vol. 43, nr 3

419-–433

EN

In this work Response Surface Methodology and Central Composite Rotatable Design were applied to find high-energy mixing process parameters enabling flow properties of highly cohesive Disulfiram powder to be improved. Experiments were conducted in a planetary ball mill. The response functions were created for an angle of repose and compressibility index as measures of powder flowability. To accomplish an optimisation procedure of mixing process parameters according to a desirability function approach, the results obtained earlier for potato starch, as another cohesive coarse powder, were also employed. Coupling these results with those achieved in a previous work, it was possible to develop some guidelines of practical importance allowing mixing conditions to be predicted towards flow improvement of fine and coarse powders.

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Studies on Moisture Effects on Powder Flow and Mechanochemical Improvement of Powder Flowability

Opaliński Ireneusz, Chutkowski Marcin, Stasiak Mateusz, Leś Karolina, Olechowski Marcin, Przywara Mateusz

Advances in Science and Technology. Research Journal

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2021

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Vol. 15, no 2

228--246

EN

Recent findings on some unsolved powder rheology problems and new challenges regarding mechanochemical powder processing and flow modelling are presented. There is remarkable difference in rheology when processing moist powders in static or dynamic conditions. Despite of regular trends of shear stress changes with humidity found in the both cases, some exceptions revealed the significant impact of particles size and their hygroscopic nature as example. Mechanochemical methods of high-energy interactive mixing of highly cohesive powders doped with nano-sized solid admixture enabled their flowability to be improved considerably. Using statistical approach, more general routine is proposed that allow the optimal mixing parameters to be reliably predicted with limited number of experiments needed. Ability to flow of some hygroscopic powders was examined with DEM method and extreme sensitivity of model output to input particle properties was found. The common DEM routine towards powder flow prediction is therefore suggested to be replaced with approach featuring in using DEM method to identify some unknown powder flow factors.

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Prospective Application of Response Surface Methodology for Predicting High-Energy Mixing Process Conditions towards Fine Powders Flow Improvement

Leś Karolina, Opaliński Ireneusz

Advances in Science and Technology. Research Journal

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2021

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Vol. 15, no 1

134--143

EN

Planetary ball mill was proposed as an intensive high-energy mixer to obtain flowability improvement of industrially exploited, cohesive and finely comminuted powders via dry coating. Response surface methodology (RSM) coupled with central composite rotatable design (CCRD) was applied as an effective method for the prediction of high-energy mixing conditions. The use of this procedure allows identifying relatively narrow ranges of high-energy mixing parameters (rotating speed of planetary ball mill and mixing time) and the amount of additives used (nanosilica and isopropyl alcohol) providing substantial improvement of the flowability of Aluminium hydroxide (Apyral) and Calcium carbonate powders. In order to find the optimal values of the process parameters, enabling to obtain the lowest values of flowability indices (angle of repose, compressibility index), the desirability function approach was applied. The obtained results may be a basis for developing a general routine allowing mixing parameters to be successfully predicted regarding some physical properties of powders only with no experiments needed.