Characterisation of solid hydrodynamics in a three-phase stirred tank reactor with positron emission particle tracking (PEPT)

Standard method for performing positron emission particle tracking (PEPT) measurements of froth flotation at PEPT Cape Town

“…Another major advantage of PEPT for flotation research is that it can be used to investigate the effect of particle properties, such as size, shape, surface hydrophobicity and density (e.g. [1 , 6 , 7 , 11] ). The tracer particle for PEPT measurements is both labelled with a positron-emitting radionuclide and has physical and chemical properties that represent those of the flotation bulk.…”

Effect of Retrofit Design Modifications on the Macroturbulence of a Three-Phase Flotation Tank─Flow Characterization Using Positron Emission Particle Tracking (PEPT)

“…Based on a Reynold’s decomposition, the velocity distribution in each voxel was split into an average i and a fluctuating component u i in each dimension i , U i = U̅ i + u i where the fluctuations were calculated as the root mean squared difference from the peak velocity value. The turbulent kinetic energy (per unit mass) , was calculated for each voxel as TKE = 1 2 ( false⟨ u r 2 false⟩ + false⟨ u θ 2 false⟩ + false⟨ u z 2 false⟩ ) All of the resulting data per voxel, including the velocity, fluctuating velocity component and TKE for each component, as well as the tracer trajectory data, has been compiled and compressed into a Data.zip file, available in an open-source data repository …”

“…The first voxel configuration was (Δr, Δθ, Δz) = (10 mm, 5°, 10 mm). 14 Four azimuthal slices taken at the midpoints between the baffles were summed at spacings of 90°, using the symmetrical proportions of the tank to maximize the number of data points within each voxel. The first voxel configuration relative to the geometries of the vessel and retrofit design modifications is shown in the Supporting Information, Figure S1, including both absolute values for the slice limits and as proportions to the vessel radius R and height H. Gaussian kernel density estimation was used to find the probability density function (PDF) of the distributions of velocity components for each voxel, and the peak of each PDF was used as the modal average of the velocity.…”

“…PEPT offers the advantage of being able to track particle flow in opaque, three phase systems, whereas other tracking techniques such as particle image velocimetry (PIV) tend to be restricted to single or two phase systems. , Since its first application to froth flotation by Waters et al, PEPT has been established as an important technique for studying the fluid dynamics of flotation systems. Recent applications of PEPT to flotation include the study of coarse particle flotation, ,, normal operating size limits and individual bubble–particle interactions …”

“…11,12 Since its first application to froth flotation by Waters et al, 13 PEPT has been established as an important technique for studying the fluid dynamics of flotation systems. Recent applications of PEPT to flotation include the study of coarse particle flotation, 2,14,15 normal operating size limits 16 and individual bubble−particle interactions. 17 Until recently, the turbulent properties of fluid behavior were not commonly calculated from PEPT data.…”