Search Results (6)

The significance of froth rheology in affecting flotation performance is widely acknowledged. Clays could deteriorate flotation performance by altering froth rheology. The presence of cations further complicates the flotation system. Thus far, the interaction between clay minerals and cations and their impact on froth rheology remains unclear. The present work selected three typical clays and cations with two valences (Na⁺ and Ca²⁺) to investigate their interacting influences on froth rheology. The results indicate that clays exhibit diverse froth rheological behaviors, with increasing cation strength from 0 to 0.1 mol/L. For montmorillonite, the froth viscosity initially decreased and subsequently increased. For kaolinite, upon the addition of cations, there was a significant decrease in froth viscosity; nevertheless, froth viscosity barely changed as the valency and concentration of the cations increased. Talc produced a considerably more viscous froth, and froth viscosity continued to rise with increasing concentrations of cations. The underlying mechanisms of the different responses in froth rheology were also investigated. The findings of this work have the potential to advance the optimization of flotation for complex ores containing clay minerals in high-salt processing water. Full article

Labradorite is a beautiful and popular mineral known for its iridescent play of colour. It is commonly found in igneous rocks and belongs to the feldspar group of minerals which are common in sulfidic Cu-Ni-PGM ores in South Africa. Labradorite primarily consists of calcium, sodium, aluminum, and silicon. There are various uses for labradorite, these range from its use as an ornamental stone to being an additive in ceramics and in glassmaking. Therefore understanding its behaviour under various water conditions is therefore important not only for froth flotation where process water of high ionic strength is used but also important for the question of how ceramics with labradorite as an additive would be affected when subjected to water of high ionic strength and water containing Ca²⁺, Mg²⁺, Cl⁻ and SO₄²⁻ ions in significant quantities. This study therefore examined the behaviour of labradorite in changing water quality, specifically of increasing ionic strength. Labradorite particles were investigated for their behaviour under varying ionic strength of water using two techniques, namely the zeta potential analyser and UV-vis spectroscopy in order to understand the impact of water quality on surface chemistry of labradorite. The zeta potential analyser was used to understand effects on the surface charge of the mineral whilst UV-vis spectroscopy was used to determine the adsorption of sodium carboxymethyl cellulose (CMC) at the mineral surface. CMC was important in this study not only because of its use in flotation as a depressant but also due to its role in materials manufacturing as a binder and rheology modifier, both of which are significant properties in the production of ceramics and pellets. The results of this study showed that the adsorption of CMC, is enhanced in water of high ionic strength. It was also shown that the electrokinetic potential of labradorite increased and became less nagative in water of higher ionic strength, thus demonstrating a passivation effect at the labradorite mineral surface. The findings of this study imply that gangue minerals associated with or of a similar nature to labradorite, such as the feldspar group of minerals in sulfide ore flotation, are likely to be depressed in flotation. Furthermore, the results from this study may be valuable for the ceramics and glassmaking industries, where labradorite is used as an additive, especially in cases where their products are exposed to harsh water conditions. Full article

The rheologic properties of a three-phase coal froth are critical to understanding the interfacial properties that are associated with its stability. Due to the fragile nature of froth, oscillatory rheology was used to make sure that the froths were not damaged during measurement. To reveal the relationship between a coal froth’s rheology and its stability, oscillatory rheology was used in this study. The viscoelastic behaviors of coal froths were analyzed, which illustrated that the storage modulus (G′) of a coal froth is larger than its loss modulus (G″), showing that coal froth is solid-like. The complex viscosity of the coal froths decreased with an increase in angular frequency, meaning that coal froth is shear-thinning. The dependence of froth rheology on ionic strength was investigated, which showed that an increase in ionic strength led to an enhancement of the storage modulus G′, as well as a decrease in tanδ (G″/G′). The coal froths tended to be more rigid and viscous with an increase in ionic strength. The mechanism of the effect of ionic strength on froth rheology was explored using electrical double layers, cryo-SEM, and particle fractions. As the ionic strength increased, the thickness of the electrical double layer decreased, which strengthened the interaction between the particles in the froth; in addition, the solid fraction in the froth increased with an increase in the ionic strength, so the value of G′ and the froth’s stability both increased. Full article

Recent years have witnessed growing research interest in applying rheology in grinding and flotation treatment of finely disseminated ores. Slurry rheology has long been identified as the comprehensive effect of inter-particle interactions, including their aggregation and dispersion states in slurry, which are more impactive under the fine-particle effect. In this regard, rheology has the potential to play a significant role in interpreting the flowing and deforming phenomena of inter-particle aggregates, particle-bubble aggregates, and flotation froth. Though much attention has been paid to the rheological effect in industrial suspension, this has not been the case for mineral grinding and flotation for fine particles. The influential mechanism of rheology on the sub-processes of mineral processing has not been systemically determined nor revealed thoroughly, thus the underpinning mechanism for enhancing the processing efficiency has been difficult to discover. This paper reviews the current application and importance of rheology in fine mineral processing, and the potential research direction in the field is proposed. Full article

In the attempt to process lower-grade ores, mineral flotation has taken centre stage as the preferred recovery route. However, in many instances, the froth product does not have a high grade due to the entrainment of gangue minerals. Industry has solved this challenge by introducing froth washing mechanisms. Clean wash water is introduced into or on top of the froth to reduce the amount of entrained gangue in the final concentrate. This article reviews froth-washing systems in detail and highlights the advantages and disadvantages of each wash-water delivery mechanism. Comments on industrial uptake are provided. The indications are that froth washing improves the grade of the concentrate and influences froth stability and mobility. Other researchers have reported an improvement in recovery—especially of coarse particles—with wash water being added, while others have reported a reduction in recovery, especially with composite particles. Froth washing is generally applied in mechanical flotation cells by washing at the lip. In column flotation cells and Jameson cells, wash water is added to the entire froth surface. The literature also indicates that the wash-water rate, wash-water quality, type of wash-water delivery/ distribution mechanism and the area covered by wash water are critical parameters that dictate the efficacy of the washing system. Further research is necessary on the impact of wash-water quality on the froth phase sub-processes including froth rheology. Full article

This paper summarizes and discusses previous investigations into the correlation between the rheology and flotation process of fine particle suspensions. This summary provides a better understanding of the challenges and current status of this subject and useful feedback based on the revision of relevant theories and practical implications for fine particle characterization and processing. Such processes include the sustainable beneficiation of complex ores and wastes for valuable material extraction and the segregation of toxic substances. For example, there has been increasing demand for the beneficiation of complex ores often carrying the values (e.g., critical raw materials) in fine grains, due to the noticeable decrease in the accessibility of high-grade and easily extractable ores. To maintain the sustainable use of limited resources, the effective beneficiation of complex ores is urgently required. It can be successfully achieved only with selective particle/mineral dispersion/liberation and the assistance of mineralogical and fine particle characterization including a proper understanding of the rheological behavior of complex ores in the context of fine particle separation/processing. In correlating flotation with suspension rheology, previous works were summarized and we found that the modeling of their correlations as well as comprehensive contributions of pulp and froth rheology on flotation performance have been studied very limitedly, and comprehensive developments in these aspects are thus strongly suggested. Full article