A comparison of different cyclones in addressing challenges in the classification of the dual density UG2 platinum ore

It is common practice in the mineral processing industry to use hydrocyclones for particle classification. However, classification in the UG2 platinum circuits using the hydrocyclone poses major challenges due to the differences in density between silica and chromite, the two major components of this ore. Silica, the PGM carrying component, has an average density of 2.7 and the barren chromite component has an average density of 4.5. When conventional and flat bottom cyclones are used there is a misplacement of particles due to differences in density leading to inefficiencies in the classification by size. As a result of the density effect, coarse silica reports to the overflow, resulting in loss of recovery, and fine chromite reports to the underflow, resulting in loss of milling capacity and unnecessary production of fine chromite. A classifier based on a different concept was required in the classification of UG2 platinum ore. The three-product cyclone, which is a hydrocyclone with two concentric vortex finders to produce three distinct products, has been tested in the UG2 ore application and indications are that misplacement of particles due to differences in the component densities can be minimized through the use of this unit. Industrial and pilot plant trials were conducted and indications are that the three-product cyclone can be installed to selectively produce a middlings stream that can be screened using Pansep screens to provide a screen oversize, which is predominantly coarse silica that can be preferentially reground to recover the PGM values contained in the coarse silica

A semi-mechanistic model of hydrocyclones - developed form industrial data and inputs from CFD.

The flow behavior in hydrocyclones is extremely complex, leading the designers to rely on empirical equations for predicting cyclone performance. A number of classifying cyclone models have been developed and used in mineral comminution circuit simulators in the past. The problem with these empirical cyclone models is that they cannot be used outside the range of conditions under which they were developed. A semi-mechanistic hydrocyclone model is developed using the dimensionless approach based on both the fluid mechanics concepts from Computational Fluid Dynamics (CFD) simulations and the wide range of industrial cyclone performance data. The improved model consist a set of equations for the water split to underflow (R), reduced cut-size (d), throughput (Q) and sharpness of the separation (α). The model for R, d, Q gives a very good fit to the data. The alpha model shows reasonable correlation for the cyclone design and operating conditions. Additional data sets were used to validate the new hydrocyclone model by comparing the predictions of the model equations with the experimental results

Improved Communication Circuit Simulations Using New Set of Equations Ofa Hydrocyclone Classifier

M Narasimha, AN Mainza, P Holtham, M Brennan and MS Powel

Multi-component modelling concept for hydrocyclone classifier

The flow in a hydrocyclone classifier is highly turbulent complex nature of multi-phase structure, which has led designers to rely on empirical mathematical models for predicting the performance. A number of classifying cyclone models have been developed and successfully used in mineral comminution circuit simulators over the past four decades (Plitt. 1976 and Nageswararao. 1978). However, most of the mathematical models currently available to describe hydrocyclone classifier performance are based on single average mineral density component behavior. In industrial comminution circuits, the feed to the cyclone composed of a mixture of particles of varying degrees of liberation and sizes. The behavior of multi-component particles in a hydrocyclone is poorly understood and unaccounted for in most of the mathematical model equations available in the literature. There is evidence from a number of experimental data sets indicating the significant influence of the multi-component particles on measured cyclone performance. A concept for modeling the performance of hydrocyclones based on multi-component behavior is proposed in this paper. A set of semi-empirical model equations for cutsize, sharpness of separation are presented and the corresponding model parameters evaluated from the measured data are given

Multi - Component modelling concept for hydrocyclone classifier

The flow in a hydrocyclone classifier is highly turbulent complex nature of multi-phase structure, which has led designers to rely on empirical mathematical models for predicting the performance. A number of classifying cyclone models have been developed and successfully used in mineral comminution circuit simulators over the past four decades (Plitt, 1976 and Nageswararao, 1978). However, most of the mathematical models currently available to describe hydrocyclone classifier performance are based on single average mineral density component behavior. In industrial comminution circuits, the feed to the cyclone composed of a mixture of particles of varying degrees of liberation and sizes. The behavior of multi-component particles in a hydrocyclone is poorly understood and unaccounted for in most of the mathematical model equations available in the literature. There is evidence from a number of experimental data sets indicating the significant influence of the multi-component particles on measured cyclone performance. A concept for modeling the performance of hydrocyclones based on multi-component behavior is proposed in this paper. A set of semi-empirical model equations for cut-size, sharpness of separation are presented and the corresponding model parameters evaluated from the measured data are given