Stirred media mills in the mining industry: Material grindability, energy-size relationships, and operating conditions

Acid-induced pea protein gels pretreated with media milling: Gelling properties and the formation mechanism

This study explored the effect of stirred media mill (SMM) processing on the acid-induced gelling properties of pea protein. Results showed that SMM treatment enhanced the gel strength from 75.06 g to 183.89 g and increased the water holding capacity from 46.64 % to 73.50 %. The minimum gelation concentration achieved for SMM-treated pea protein was 4 %, significantly lower than that of heat-pretreated pea protein (9 %). SMM decreased protein aggregate size from 104 μm to 180 nm. Microscopy analysis revealed that the small aggregates facilitated the formation of uniform gel networks with tight connections. Linear rheology indicated that small protein aggregates resulted in slower gelation rates with a higher G' for the formed gels. The SMM-pretreated protein gel showed strain hardening, shear thinning behaviors, and satisfactory stability to withstand large-amplitude oscillatory shear. Overall, SMM emerges as a promising technology for producing protein gel products with strong mechanical attributes and customizable rheological properties.

Analysis and Optimization of the Milling Performance of an Industry-Scale VSM via Numerical Simulations

Vertical stirred mills (VSM) are widely used for powder processing in many situations like mechanical alloying preparation and raw material crushing and shaping. Many structural and operational parameters like stirrer helix angle and rotating speed have great significance on VSM performance, especially in a large industry-scale situation. Therefore, it becomes essential to investigate these parameters systematically to obtain high energy efficiency and good product quality. In this work, the discrete element method (DEM) was used to examine the effects of stirrer helix angle (α), stirrer diameter (d), and rotating speed (n) on the grinding performance in an industrial VSM, and then the response surface method (RSM) was employed for multi-objective optimization in the VSM. It is found that a media vortex phenomenon may happen near the stirring shaft. The media collisions are significantly influenced by α, d, and n. Through multi-objective optimization design (MOD), the power consumption (P) of the stirrer reduced by 8.09%. The media collision energy (E) increased by 9.53%. The energy conversion rate (R) rises by 20.70%. The collision intensity and frequency are both improved. This optimization method can help determine good operating parameters based on certain structures.

Starch physical treatment, emulsion formation, stability, and their applications

Pickering emulsions are increasingly preferred over typical surfactant-based emulsions due to several advantages, such as lower emulsifier usage, simplicity, biocompatibility, and safety. These types of emulsions are stabilized using solid particles, which produce a thick layer at the oil-water interface preventing droplets from aggregating. Starch nano-particles (SNPs) have received considerable attention as natural alternatives to synthetic stabilizers due to their unique properties. Physical formulation processes are currently preferred for SNP production since they are environmentally friendly procedures that do not require the use of chemical reagents. This review provides a thorough overview in a critical perspective of the physical processes to produce starch nano-particles used as Pickering emulsion stabilizers, fabricated by a 2-step process. Specifically, the reviewed physical approaches for nano-starch preparation include high hydrostatic pressure, high pressure homogenization, ultrasonication, milling and antisolvent precipitation. All the essential parameters used to evaluate the effectiveness of particles in stabilizing these systems are also presented in detail, including the hydrophobicity, size, and content of starch particles. Finally, this review provides the basis for future research focusing on physical nano-starch production, to ensure the widespread use of these natural stabilizers in the ever-evolving field of food technology.

Toward Thermochromic VO2 Nanoparticles Polymer Films Based Smart Windows Designed for Tropical Climates

Thermochromic smart windows have been extensively investigated due to two main benefits: first, the comfort for people in a room through avoiding high temperatures resulting from solar heating while taking advantage of the visible light, and second, the energy efficiency saving offered by using those systems. Vanadium dioxide (VO₂) is one of the most used materials in the development of thermochromic devices. The countries located in the tropics show little use of these technologies, although studies indicate that due to their characteristics of solar illumination and temperature, they could benefit greatly. To optimize and achieve maximum benefit, it is necessary to design a window that adjusts to tropical conditions and at the same time remains affordable for extensive implementation. VO₂ nanoparticles embedded in polymeric matrices are an option, but improvements are required by means of studying different particle sizes, dopants and polymeric matrices. The purpose of this review is to analyze what has been regarding toward the fabrication of smart windows based on VO₂ embedded in polymeric matrices for tropical areas and provide a proposal for what this device must comply with to contribute to these specific climatic needs.

Simulation of Electrical and Thermal Properties of Granite under the Application of Electrical Pulses Using Equivalent Circuit Models

Since energy efficiency in comminution of ores is as small as 1% using a mechanical crushing process, it is highly demanded to improve its efficiency. Using electrical impulses to selectively liberate valuable minerals from ores can be a solution of this problem. In this work, we developed a simulation method using equivalent circuits of granite to better understand the crushing process with high-voltage (HV) electrical pulses. From our simulation works, we calculated the electric field distributions in granite when an electrical pulse was applied. We also calculated other associated electrical phenomena such as produced heat and temperature changes from the simulation results. A decrease in the electric field was observed in the plagioclase with high electrical conductivity and void space. This suggests that the void volume in each mineral is important in calculating the electrical properties. Our equivalent circuit models considering both the electrical conductivity and dielectric constant of a granite can more accurately represent the electrical properties of granite under HV electric pulse application. These results will help us better understand the liberation of minerals from granite by electric pulse application.

Grinding Media Motion and Collisions in Different Zones of Stirred Media Mills

Product fineness during grinding in stirred media mills is mainly influenced by the specific energy input, the stress energy transferred by the colliding grinding media and the stress frequency. The stress energy from grinding media collisions is heterogeneously distributed in stirred media mills. Herein, in order to characterize the stress energy distribution and the local grinding media collision frequencies, the grinding media motion was calculated using discrete element method (DEM) simulations coupled with computational fluid dynamics (CFD). The local grinding media concentration, velocity profiles, grinding media collisions and stress energies were compared for varied total grinding media fillings and stirrer speeds. It was confirmed that the normalized grinding media velocity profile can be used to divide the grinding chamber into four types of zones that allow the modeling of the stress energy distribution. However, the collision frequency showed very different distributions for varied stirrer velocities and grinding media fillings.