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Morphological changes of glass bead particles upon an abrasive blasting as characterized by settling and flotation experiments

Behzad Vaziri Hassas, Güven Onur, Baştürkcü Esra, Çelik Mehmet S.

Physicochemical Problems of Mineral Processing

2021

Vol. 57, iss. 2

157--168

The recent developments in mineral processing led researchers to look for alternative methods and propose new mechanisms for enhancing the efficiency of relatively costly processes (e.g., flotation, aggregation), where especially dealing with fine particles. Finer the particles, the higher the role of their surface on their behavior and properties. The importance of particle morphology becomes even clearer when particle-particle and particle-bubble interactions are considered. In this study, the effect of particle shape “roundness” on the surface wettability and flotation response was investigated upon producing fine particles with the “abrasion blasting” method. In order to provide a fundamental perspective, adsorption measurements were also carried out along with the flotation experiments under the same conditions. In addition to these, zeta potential measurements were also carried out with both spherical and blasted particles as a function of collector concentration. The results suggested that the roundness of particles decreased up to a certain nozzle pressure value, which was followed by higher adsorption degrees and consequently higher flotation recoveries. Additionally, settling rate tests were also performed with very fine material to show the effect of particle morphology on particle-particle interactions. The results showed that while lower settling rate values were obtained for spherical ones, higher values were obtained in the case of the ground and blasted samples in the presence of DI water. It was concluded from this study that the “Abrasive blasting method” could be an effective alternative for tuning the surface morphology of particles and their wettability, which in turn can affect the particleparticle interactions in the system.

A simplified analysis of the effect of nano-asperities on particle-bubble interactions

Drelich J. W.

Physicochemical Problems of Mineral Processing

2018

Vol. 54, iss. 1

10--18

The interactions of gas bubbles with particles having rough and heterogeneous surfaces are much more complex than the commonly used DLVO – based models predict. The effects of surface roughness on flotation and particle – bubble interactions have been reported many times in the past, although a clear understanding of their origins has been lacking. To explain differences in interactions for spherical hydrophobic particles, a theoretical analysis of the interaction potential was carried out for a model rough particle interacting with a bubble surface in an electrolyte solution in this study. The attractive hydrophobic interaction potential was added to repulsive retarded van der Waals and repulsive electrical double layer interaction potentials. The rough microscopic particles were modeled as spheres decorated with nano-sized asperities. Parameters that reflect common flotation separation systems were selected for testing this theoretical model and computation of the energy barrier applicable to particle – flat bubble surface interactions. It was found that hydrophobic asperities with a height of only several nanometers can reduce the repulsive interaction energy by an order of magnitude. Theoretical analysis also reveals that surface coverage of microscopic particles by nano-sized asperities is important as well.