The Experts below are selected from a list of 4323 Experts worldwide ranked by ideXlab platform
J J Cilliers - One of the best experts on this subject based on the ideXlab platform.
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a general model for hydrocyclone Partition Curves
Chemical Engineering Journal, 1999Co-Authors: M Fracho, J J CilliersAbstract:Abstract The Partition Curve is used to quantify the classification in hydrocyclones. It is generally monotonic and asymptotes to a value called the bypass. A `fish-hook' Curve occurs sometimes when Partition values lower than the bypass are observed. A number of attempts have been made to develop fish-hook Partition Curve models. These are reviewed and shown to reduce to a general form. The general equation consists of two competing effects: that of classification, described by a conventional corrected Partition Curve, and that of dispersion, described by an inverse corrected Partition Curve that is applied to only the bypass fraction. A turbulence model for two-phase systems that quantifies the relative effects of dispersion and classification is described and shown to be applicable to this system. This allows some physical interpretation of the effect of variables on the observed performance. A series of small diameter hydrocyclone experiments illustrate the use of the model and are used to evaluate the bypass. It is often assumed that the bypass can be estimated accurately from the fraction of water in the feed that reports to the coarse product stream. It was, however, found that the recovery of water to the underflow was significantly lower than either the lowest point of the Partition Curve or the value of the bypass. Further work is required to conclusively determine the variation in the bypass with operating conditions.
Ian K. Craig - One of the best experts on this subject based on the ideXlab platform.
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Coal dense medium separation dynamic and steady-state modelling for process control
Minerals Engineering, 2014Co-Authors: Ewald Jonathan Meyer, Ian K. CraigAbstract:Abstract Coal dense medium separation is a popular beneficiation process used for the upgrading of coal ore into power station and metallurgical coal. The control systems used in coal beneficiation are often limited to localised regulatory control of feed rate and medium density. A coal dense medium separation process can benefit substantially from process control provided that a dynamic model for this process is available as was previously developed by the authors for a fine coal dense medium cyclone (DMC) circuit. In this paper, the previous model is adapted to a coarse coal DMC circuit and validated over a wider range of operating conditions using real plant data. The model is further validated by reducing it to steady-state to form a Partition Curve. This Curve is then compared to one derived from actual production data. The derived model is able to provide an estimate of the DMC overflow coal product that should be sufficient for process control.
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Development of a Steady-State Partition Curve from a Dense Medium Cyclone Dynamic Model in Coal Beneficiation
IFAC Proceedings Volumes, 2011Co-Authors: Ewald Jonathan Meyer, Ian K. CraigAbstract:Abstract A Partition Curve is used in dense medium separation to determine the efficiency of the separation of clean coal from discard. The method used to determine a Partition Curve in coal beneficiation is float and sink analysis. The float and sink dry masses are determined at each density fraction only after complete separation of the material has taken place. This means that the Partition Curve is a form of a steady-state model. A dynamic model for a dense medium separation circuit is available from first principles. This paper shows how a steady-state model is derived from the dynamic model to generate a Partition Curve. This Partition Curve is compared with plant measurements taken from a plant operation.
Jan J. Cilliers - One of the best experts on this subject based on the ideXlab platform.
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sub micron particle dewatering using hydrocyclones
Chemical Engineering Journal, 2000Co-Authors: S Pasquier, Jan J. CilliersAbstract:Hydrocyclones are used for dewatering of solid–liquid suspensions in many industries. Generally, however, large diameter cyclones are used and their application is restricted to large (>25 μm) particles. Small diameter (10 mm) hydrocyclones have the potential to be applied to fine particle (<10 μm) suspensions and, in particular, to collect the sub-micron fraction. This is due to the very small cutsizes that are achieved in these cyclones. In order to apply these small hydrocyclones industrially, knowledge of the range of their classification performance is required. It is found that these cyclones exhibit a fish-hook Partition Curve, and a high bypass fraction. The very small cutsize (<5 μm) and the relatively large bypass makes the effective collection of sub-micron particles possible. While in most hydrocyclone applications it is found that the bypass fraction equals the water recovery to the underflow, in 10 mm hydrocyclones the bypass fraction is considerably larger than the water recovery. This results in a high particle recovery to the underflow, as well as low water recovery, resulting in a high concentration ratio. Results will be presented to show the separation performance of different hydrocyclone outlet configurations and pressure drops. A general model will be presented that describes the fish-hook and that gives an explanation for its origin. It will be shown that 10 mm hydrocyclones yield a new operating regime for their application to sub-micron solid–liquid separation, as a result of high solids recoveries and low water recoveries.
M Fracho - One of the best experts on this subject based on the ideXlab platform.
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a general model for hydrocyclone Partition Curves
Chemical Engineering Journal, 1999Co-Authors: M Fracho, J J CilliersAbstract:Abstract The Partition Curve is used to quantify the classification in hydrocyclones. It is generally monotonic and asymptotes to a value called the bypass. A `fish-hook' Curve occurs sometimes when Partition values lower than the bypass are observed. A number of attempts have been made to develop fish-hook Partition Curve models. These are reviewed and shown to reduce to a general form. The general equation consists of two competing effects: that of classification, described by a conventional corrected Partition Curve, and that of dispersion, described by an inverse corrected Partition Curve that is applied to only the bypass fraction. A turbulence model for two-phase systems that quantifies the relative effects of dispersion and classification is described and shown to be applicable to this system. This allows some physical interpretation of the effect of variables on the observed performance. A series of small diameter hydrocyclone experiments illustrate the use of the model and are used to evaluate the bypass. It is often assumed that the bypass can be estimated accurately from the fraction of water in the feed that reports to the coarse product stream. It was, however, found that the recovery of water to the underflow was significantly lower than either the lowest point of the Partition Curve or the value of the bypass. Further work is required to conclusively determine the variation in the bypass with operating conditions.
Ewald Jonathan Meyer - One of the best experts on this subject based on the ideXlab platform.
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Coal dense medium separation dynamic and steady-state modelling for process control
Minerals Engineering, 2014Co-Authors: Ewald Jonathan Meyer, Ian K. CraigAbstract:Abstract Coal dense medium separation is a popular beneficiation process used for the upgrading of coal ore into power station and metallurgical coal. The control systems used in coal beneficiation are often limited to localised regulatory control of feed rate and medium density. A coal dense medium separation process can benefit substantially from process control provided that a dynamic model for this process is available as was previously developed by the authors for a fine coal dense medium cyclone (DMC) circuit. In this paper, the previous model is adapted to a coarse coal DMC circuit and validated over a wider range of operating conditions using real plant data. The model is further validated by reducing it to steady-state to form a Partition Curve. This Curve is then compared to one derived from actual production data. The derived model is able to provide an estimate of the DMC overflow coal product that should be sufficient for process control.
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Development of a Steady-State Partition Curve from a Dense Medium Cyclone Dynamic Model in Coal Beneficiation
IFAC Proceedings Volumes, 2011Co-Authors: Ewald Jonathan Meyer, Ian K. CraigAbstract:Abstract A Partition Curve is used in dense medium separation to determine the efficiency of the separation of clean coal from discard. The method used to determine a Partition Curve in coal beneficiation is float and sink analysis. The float and sink dry masses are determined at each density fraction only after complete separation of the material has taken place. This means that the Partition Curve is a form of a steady-state model. A dynamic model for a dense medium separation circuit is available from first principles. This paper shows how a steady-state model is derived from the dynamic model to generate a Partition Curve. This Partition Curve is compared with plant measurements taken from a plant operation.