Assessing the influence of viscosity and milling bead size on the stressing conditions in a stirred media mill by single particle probes

Tailoring hydroxyapatite suspensions by stirred bead milling

“…It indicates that a higher process energy efficiency is reached in highly loaded suspensions. Similar results were observed on the dispersion of TiO 2 [56] but an opposite effect was reported on other materials [38,58] for which an inverse proportion between milling efficiency (capturing efficiency of the product particles by milling beads collisions) and suspension viscosity was observed. In the present study, such an effect was not noticeable.…”

Role of sodium hexametaphosphate in ultra-fine grinding of alumina-doped titanium dioxide

“…This concentration lowered the suspension yield stress from 27 Pa to 1.5 Pa, but increased the high shear suspension viscosity from 0.18 Pa.s to 0.48 Pa.s. The increase in suspension viscosity was reasoned to be critical in maintaining friction between the media beads and particles, but contrasted the study of Strobel et al 10 Bernhardt et al 14 studied the stirred media milling of limestone, evaluating the effects of solids concentration, from 20 to 60 wt%, with and without the addition of 0.5% sodium polyacrylate (SPA). Increasing the slurry concentration from 20 to 35 wt% and without SPA, an increase in the energy utilisation was observed, with the breakage performance increasing due to increased probability of particles being captured between media bead collisions.…”

“…7,8 The high energy demands of the milling operation can be partly offset by milling high concentration slurries, although there is an optimum to be achieved by balancing the solids throughput and the slurry viscosity; too high a viscosity and the kinetic energy by bead collision will be damped which results in poor energy transfer to the particles, significantly hindering milling performance. 9,10 The effect of suspension viscosity on the frequency of media bead collision was computationally studied by Strobel et al, 10 demonstrating that more viscous fluids also reduce the frequency of media bead collision, with the suspended particles having a greater tendency to follow the flow perpendicular to the approaching media beads.…”

Sustainable Beckmann Rearrangement using Bead‐Milling Technology: The Route to Paracetamol

“…Thus, the overall performance is driven by the probability of the chemicals to be mechanically processed by the milling beads, respectively by the probability of the particles to be trapped in an active grinding zone by a grinding bead with sufficient energy to induce the reaction. [32] Herein, the bead milling technology in a Dyno®-mill was used for the mechanochemical Beckmann rearrangement (BKR) reaction, finalized to the preparation of the WHO essential medicine paracetamol. [10] To benchmark the sustainability of this approach, comparative green metrics calculations were done for the bead milling process and compared with the current Beckmann rearrangement production process in solution use at commercial scale.…”

“…The large quantity of beads aims to maximize the occurring transferred energy per stress event and the number of stress events per unit of time. Thus, the overall performance is driven by the probability of the chemicals to be mechanically processed by the milling beads, respectively by the probability of the particles to be trapped in an active grinding zone by a grinding bead with sufficient energy to induce the reaction [32] …”