2691
Evaluation of Turbulence in a NextSTEP™ Flotation Cell Using
Piezoelectric Vibration Sensors in Multiphase Flows
Hifsa Pervez
Institute for Process Engineering and Environmental Technology, Technische Universität Dresden, Dresden, Germany
Anna-Elisabeth Sommer, Till Zürner
Institute of Fluid Dynamics, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany
Kerstin Eckert
Institute for Process Engineering and Environmental Technology, Technische Universität Dresden, Dresden, Germany
Institute of Fluid Dynamics, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany
ABSTRACT: Optimizing flotation recovery is key for meeting the current demand for minerals. However, one
of the main drivers of the process, turbulence, is especially difficult to quantify in multiphase systems. Due to
equipment complexity and opacity, optical methods are rarely used for industrial applications. We present an
enhanced system for the real-time measurement of turbulent kinetic energy (TKE) in flotation cells. Using a
piezoelectric sensor and advanced signal processing, multiple tests were performed in a nextSTEP™ lab-scale
flotation cell. The TKE was further validated with Particle Image Velocimetry (PIV) measurements to improve
system robustness. It is observed that the force measurements from the piezosensor showed higher magnitude in
the rotor-stator region and the force signal was larger in two-phase (liquid-gas) flow compared to single-phase
(liquid).
Keywords: multiphase flow, turbulence, froth flotation, piezoelectric vibration sensor
INTRODUCTION
Froth flotation is an important mineral separation tech-
nique that has revolutionized the mining industry. It
involves the use of a complex physical and chemical process
to separate valuable minerals from unwanted gangue min-
erals. The process is highly selective and has been expanded
to treat a wide range of ores, including low-grade and com-
plex ones (Wills &Finch, 2016). Turbulence is important
in froth flotation because it affects, beside bubble breakup
and coalescence (Liao &Lucas, 2009), the collision fre-
quency (Liao et al., 2015) and hence the key sub-processes,
particle-bubble collision, and attachment (Dai et al., 1999
Nguyen &Schulze, 2003) and detachment of bubblepar-
ticle (Wang et al., 2014). The inherent stochastic nature
of turbulence in the continuous phase is further compli-
cated by the random distribution of the dispersed phase.
The presence of the dispersed phase makes both experimen-
tal measurements and numerical simulations of turbulent
multiphase flows far more difficult than those of single-
phase flows (Lee et al., 1987 Liao et al., 2015).
Key turbulence parameters such as the turbulent kinetic
energy (TKE) and turbulent kinetic energy dissipation rate
Evaluation of Turbulence in a NextSTEP™ Flotation Cell Using
Piezoelectric Vibration Sensors in Multiphase Flows
Hifsa Pervez
Institute for Process Engineering and Environmental Technology, Technische Universität Dresden, Dresden, Germany
Anna-Elisabeth Sommer, Till Zürner
Institute of Fluid Dynamics, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany
Kerstin Eckert
Institute for Process Engineering and Environmental Technology, Technische Universität Dresden, Dresden, Germany
Institute of Fluid Dynamics, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany
ABSTRACT: Optimizing flotation recovery is key for meeting the current demand for minerals. However, one
of the main drivers of the process, turbulence, is especially difficult to quantify in multiphase systems. Due to
equipment complexity and opacity, optical methods are rarely used for industrial applications. We present an
enhanced system for the real-time measurement of turbulent kinetic energy (TKE) in flotation cells. Using a
piezoelectric sensor and advanced signal processing, multiple tests were performed in a nextSTEP™ lab-scale
flotation cell. The TKE was further validated with Particle Image Velocimetry (PIV) measurements to improve
system robustness. It is observed that the force measurements from the piezosensor showed higher magnitude in
the rotor-stator region and the force signal was larger in two-phase (liquid-gas) flow compared to single-phase
(liquid).
Keywords: multiphase flow, turbulence, froth flotation, piezoelectric vibration sensor
INTRODUCTION
Froth flotation is an important mineral separation tech-
nique that has revolutionized the mining industry. It
involves the use of a complex physical and chemical process
to separate valuable minerals from unwanted gangue min-
erals. The process is highly selective and has been expanded
to treat a wide range of ores, including low-grade and com-
plex ones (Wills &Finch, 2016). Turbulence is important
in froth flotation because it affects, beside bubble breakup
and coalescence (Liao &Lucas, 2009), the collision fre-
quency (Liao et al., 2015) and hence the key sub-processes,
particle-bubble collision, and attachment (Dai et al., 1999
Nguyen &Schulze, 2003) and detachment of bubblepar-
ticle (Wang et al., 2014). The inherent stochastic nature
of turbulence in the continuous phase is further compli-
cated by the random distribution of the dispersed phase.
The presence of the dispersed phase makes both experimen-
tal measurements and numerical simulations of turbulent
multiphase flows far more difficult than those of single-
phase flows (Lee et al., 1987 Liao et al., 2015).
Key turbulence parameters such as the turbulent kinetic
energy (TKE) and turbulent kinetic energy dissipation rate