Different Flotation Performance of Ultrafine Scheelite under Two Hydrodynamic Cavitation Modes

Abstract

Abstract:In industrial practice, hydrodynamic cavitation (HC) is commonly triggered by jetting either reagent solution or pulp. Although both methods can enhance mineral flotation, are their roles the same? There are few research studies in the field, which severely limits our understanding on mineral flotation combined with HC. Therefore, in this study, the flotation of ultrafine scheelite with HC pretreatments of reagent solution and pulp (abbreviated to be HCPS and HCPP, respectively) was studied and compared through flotation tests, zeta potential analysis, microscope tests, and shear yield stress measurements. The results of flotation tests show that both HCPS and HCPP can enhance the final flotation performance, but in general, HCPP leads to greater improvements on the final flotation recovery. The presence of (hydrophobized) scheelite particles brings extra gas nuclei for the cavitation-flotation system, suggesting that more NBs may be produced in the case of HCPP compared with HCPS. These tiny bubbles remarkably reduce the size distribution of bubbles in the flotation system, thus increasing the particle-bubbles collision probability. Increase in particle aggregation may be another reason why flotation with HCPP results in a higher flotation recovery. The adherence of NBs on hydrophobized particles decreases the (absolute) surface charge of the solids, resulting in a smaller repulsive force among particles and more significant particle aggregation, which is confirmed by the microscope tests and shear yield stress measurements.

Role of mineral flotation technology in improving bitumen extraction from mined Athabasca oil sands—II. Flotation hydrodynamics of water‐based oil sand extraction

“…In addition, increasing the dissolved gas content also led to a decrease in the fluid flow velocity required for the cavitation inception of generating nanobubbles . The presence of hydrophobic particles in water was found to be favourable for cavitation, verifying that feed pre‐aeration by hydrodynamic cavitation could be more effective for increasing flotation recovery than by generating nanobubbles in water alone …”

“…Such a unique feature allows the design of a robust flotation system for a wide range of feed particle sizes. Enhanced flotation separation efficiency with a similar, or even a better concentrate grade, in addition to increased recovery and flotation kinetics; As shown in Figure , cavitation tube spargers gave the highest minerals and bitumen recovery, virtually without reducing its froth quality or separation efficiency. Cavitation tubes can also be used to pre‐aerate the feed, by pumping the feed to a flotation column or any other type of flotation cells via cavitation tubes, for increased unit flotation recovery and reduced reagent consumptions Cavitation generated nanobubbles have been successfully tested and/or applied to commercial operations to enhance the flotation recovery of different types of ores and materials such as oxide minerals, industrial minerals, sulphide minerals, coal, oil sands, etc …”

“…In oil sands FPW, the zeta‐potential was relatively constant at around −20 mV and was virtually unaffected by pH because of the high concentration of ionic species present . The less negatively charged air nanobubbles generated by hydrodynamic cavitation were found to enhance aggregation and flotation recovery of ultrafine scheelite …”

Effect of Nanobubbles on the Flotation Behavior of Microfine-Grained Serpentine

“…Still, with the depletion of highquality resources, it becomes necessary to process poor ores with extremely fine inlay grain size, which is somewhat overwhelming for conventional flotation techniques. In this regard, numerous studies have found that nanobubble flotation can improve the flotation of fine-grained minerals [2,3]. Nanobubbles, alternatively referred to as microbubbles, are minute bubbles with diameters measuring less than 1 µm [4].…”

Effect of Hydrodynamic Cavitation Assistance on Different Stages of Coal Flotation

“…The application of HC in flotation has been reported in recent years. Some researchers have used HC as a pulp pretreatment method before flotation [8][9][10][11][12][13]. Other studies have used HC in flotation separation processes; the tests are usually carried out in flotation columns [14][15][16][17].…”