Influence Mechanism of Magnetized Modified Kerosene on Flotation Behavior of Molybdenite

The effects and mechanism of magnetized kerosene on the flotation behaviors of molybdenite were studied by micro-flotation, ultraviolet spectrum, infrared spectrum, surface tension, and liquid viscosity. According to the results of micro-flotation, magnetized kerosene improved the flotation recovery of molybdenite, and the improvements were more obvious with smaller molybdenite particles. Spectral analysis showed that the magnetization did not change the chemical composition of kerosene, but transformed the linear aliphatic hydrocarbons in kerosene into linear isomers and reduced the lengths of the carbon chains. Moreover, the magnetization reduced the viscosity of kerosene and oil/water interfacial tension, and improved the dispersion of kerosene in the pulp. The external magnetic field transformed the disorder of the additional magnetic moment in the kerosene molecules into order, and reduced the compactness of the kerosene molecules. The experimental results provided a theoretical explanation for the role of magnetization in mineral flotation.

Wall shear stress from jetting cavitation bubbles: influence of the stand-off distance and liquid viscosity

We study systematically the cavitation-induced wall shear stress on rigid boundaries as a function of liquid viscosity $\mu$ and stand-off distance $\gamma$ using axisymmetric volume of fluid (VoF) simulations. Here, $\gamma =d/R_{max}$ is defined with the initial distance of bubble centre from the wall $d$ and the bubble equivalent radius at its maximum expansion $R_{max}$ . The simulations predict accurately the overall bubble dynamics and the time-dependent liquid film thickness between the bubble and the wall prior to the collapse. The spatial and temporal wall shear stress is discussed in detail as a function of $\gamma$ and the inverse Reynolds number $1/Re$ . The amplitude of the wall shear stress is investigated over a large parameter space of viscosity and stand-off distance. The inward stress is caused by the shrinking bubble and its maximum value $\tau _{mn}$ follows $\tau _{mn} Re^{0.35}=-70\gamma +110$ (kPa) for $0.5<\gamma <1.4$ . The expanding bubble and jet spreading on the boundary produce an outward-directed stress. The maximum outward stress is generated shortly after impact of the jet during the early spreading. We find two scaling laws for the maximum outward stress $\tau _{mp}$ with $\tau _{mp} \sim \mu ^{0.2} h_{jet}^{-0.3} U_{jet}^{1.5}$ for $0.5\leq \gamma \leq 1.1$ and $\tau _{mp} \sim \mu ^{-0.25} h_{jet}^{-1.5} U_{jet}^{1.5}$ for $\gamma \geq 1.1$ , where $U_{jet}$ is the jet impact velocity and $h_{jet}$ is the distance between lower bubble interface and wall prior to impact.

Characteristics of secondary droplets produced by the impact of drops onto a smooth surface

This work investigates the splashing behaviors of droplets impacting on solid surfaces and mainly focuses on the characteristics of secondary droplets. According to the experimental results, two different splashing patterns, corona splash and levitating-lamella breakup, are observed. A new breakup mode, named rim-segmenting, is found during the levitating-lamella breakup. In particular, the detailed information of the splashing secondary droplets, including the size, velocity, angle, and total volume of the splashing secondary droplets is obtained from the experimental data. The size distribution of the splashing secondary droplets obeys the gamma distribution function. The average diameter and splashing angle of the secondary droplets are mainly related to the Reynolds number Re, and can be expressed as functions of Re. High impact velocity and liquid viscosity will result in a wider size distribution range of splashing secondary droplets. We also put forward an empirical model to predict the total splashing volume, which is consistent with the experimental data both in this work and previous studies. This work is believed to provide insights on the prediction of the characteristics of splashing secondary droplets.

Parameters Affecting Efficiency of Centrifugal Pump - A Review

The pump is used as one of the most significant components in chemical industry so without its existence process may not be completed, because for any fluid to flow, initial driving force is required and it is fulfilled by the pump by consuming electrical energy and converting it to pressure energy. So, the selection of pump is very important in every field of section, depending on the property of process fluid. The Centrifugal pump is most demanding nowadays because it has simple design, less maintenance, can handle large quantities of fluids, and provides very high flow rates. The Centrifugal pump has mainly two components rotating components and stationary components. Shaft and impeller (open, semi-enclosed, and fully-enclosed) comes under the category of rotating components and casing (Volute, Vortex, and circular) comes under stationary components. Various parameters of process fluid like liquid viscosity, temperature, specific gravity, vapor pressure, concentration, shear sensitive and abrasive or non-abrasive, MOC, pump environment, pressure, flow rate, etc. are calculated to gain the desired efficiency and prevent a problem like cavitation if not properly handled. In this paper, a single-stage centrifugal pump is reviewed and studied how to increase performance and efficiency of centrifugal pump.