The settling behaviour and rheological properties of microbubble-laden froth

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology Pub Date : 2025-03-31 DOI:10.1016/j.powtec.2025.120999

Liang Cao, Yongjun Peng

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Abstract

In resource processing plants, dewatering froth concentrates is typically challenging due to the strong network structure of particles formed at the plateau borders of stable froth as observed in previous studies. However, these studies have overlooked the impact of bubbles which are essential components of froth. Given the unique properties of microbubbles, such as their ability to reduce the diffusion rate of core gas and withstand mechanical stresses, the objectives of this study were to determine whether microbubbles exist in stable froth and to assess their effect on froth settling. Through settling tests and microscopy analysis, we confirmed the presence of microbubbles (<100 μm) alongside macrobubbles (>100 μm) in stable froth. The results revealed that macrobubble-laden froth readily coalesced during settling, whereas microbubble-laden froth maintained its integrity and moved upwards. Structural analysis further demonstrated that microbubble-laden froth, in contrast to macrobubble-laden froth, was densely packed with finer particles. The small radii of the microbubbles enhanced capillary forces, promoting particle adhesion to bubble surfaces and reducing the likelihood of particle detachment. In addition, amplitude sweep analysis in the oscillatory rheology measurement discovered that the unsettled microbubble-laden froth exhibited a wider linear viscoelastic (LVE) range and lower complex modulus (G*), indicating the froth possessing greater structural resilience with less rigidity under deformation. Meanwhile, frequency sweep analysis discovered lower storage modulus (G′) and loss modulus (G″) values of the unsettled microbubble-laden froth, suggesting that the froth, despite displaying a solid-like behaviour, was characterized by weaker particle interactions and a softer structural framework. These results indicated that the microbubble-laden froth possessed greater adaptability and structural compliance, enabling it to maintain integrity during the settlement process as the root cause of the difficult settling of stable froth.

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来源期刊

Powder Technology 工程技术-工程：化工

CiteScore

9.90

自引率

15.40%

发文量

1047

审稿时长

46 days

期刊介绍： Powder Technology is an International Journal on the Science and Technology of Wet and Dry Particulate Systems. Powder Technology publishes papers on all aspects of the formation of particles and their characterisation and on the study of systems containing particulate solids. No limitation is imposed on the size of the particles, which may range from nanometre scale, as in pigments or aerosols, to that of mined or quarried materials. The following list of topics is not intended to be comprehensive, but rather to indicate typical subjects which fall within the scope of the journal's interests: Formation and synthesis of particles by precipitation and other methods. Modification of particles by agglomeration, coating, comminution and attrition. Characterisation of the size, shape, surface area, pore structure and strength of particles and agglomerates (including the origins and effects of inter particle forces). Packing, failure, flow and permeability of assemblies of particles. Particle-particle interactions and suspension rheology. Handling and processing operations such as slurry flow, fluidization, pneumatic conveying. Interactions between particles and their environment, including delivery of particulate products to the body. Applications of particle technology in production of pharmaceuticals, chemicals, foods, pigments, structural, and functional materials and in environmental and energy related matters. For materials-oriented contributions we are looking for articles revealing the effect of particle/powder characteristics (size, morphology and composition, in that order) on material performance or functionality and, ideally, comparison to any industrial standard.