TY - BOOK

T1 - Optimization of Classification Results by Controlling of Hydrocyclone Process Parameters

AU - Van Ommen, Roman

N1 - no embargo

PY - 2011

Y1 - 2011

N2 - This work is an attempt to investigate the influence of a hydrocyclone density regime on a closed circuit grinding system to the circuit product quality. The majority of the research work done on hydrocyclones was made on open systems, however very little work was done on closed circuit grinding systems. As grinding is one of the most expensive steps in mineral processing it is of high economic interest to investigate the cyclones influence to the overall circuit performance. The overall performance of a grinding circuit can be altered by just changing the Apex diameter. Technical results On the technical side answers to the following points were found and qualified: Apex capacity and cyclone cone angle Achievable underflow density with varying particle size distribution Basic reaction of the grinding circuit to cyclone underflow density variation oThe influence of underflow density to the circulating load of a closed grinding circuit oThe influence of circulating load to slurry viscosity in closed circuit grinding oThe influence of underflow density to hydrocyclone D50 in closed circuit grinding oThe influence of underflow density to the overflow product quality in closed circuit grinding oThe content of misplaces particles with decreasing apex diameter. Recovery curve shapes and cyclone simulation For the complete evaluation of the recovery curve also the upper and the lower ends have to be looked at. Cyclone performance simulation is split into two different disciplines which is the establishing of the cyclone D50 and the realistic modelling of the shape of the estimated recovery curve which is done today with the Lynch Rao equation.The resulting curve is symmetrical around the D50 point. The upper and lower tails of this model are symmetrical and cannot be shaped differently. Systematic test work, as well as plant data, show that the shape of the upper and the lower tail of the recovery curve vary significantly with the variation of the water split in the hydrocyclone. To mitigate the shortcomings of the symmetrical approach, an improved equation for the modelling of the recovery curve is needed to provide the possibility to modify the shape of the upper and the lower tail of the recovery curve independently to adjust for varying water splits, but at the same time the approximated linear shape around the D50 should be maintained. A perfect fit with real data was found with a modified equation which is called weighted two parameter Lynch-Rao function. This weighted two parameter Lynch-Rao function is now much more suitable to describe the partition curve of a hydrocyclone under varying water splits. It is suitable for both, simulating and analyzing hydrocyclone performance more precisely as when using the symmetrical model. Economical results All operational and strategic efforts must strive towards the achievement of best operating practices as these directly translate to cash flow. The most important step to best practices is proper knowledge management and the understanding, recognizing, and growth of a firms’ intellectual capital. Two main technical approaches can be made on hydrocyclone economics. First the reduction of operating pressure which leads to savings in energy and maintenance cost. Second improved density regimes lead to improved separation and grinding circuit performance. •Improved recovery results in more product and enhanced revenues •Higher recovery leads to better utilization of exhaustible, non-renewable resources and thus increases the amount of recoverable reserves on a company, national and global level •Lower power requirements result in a reduction of operating costs leading to higher profits at given revenues •Lower power requirements result in a reduction of power-related environmental effects, notably CO2-emissions

AB - This work is an attempt to investigate the influence of a hydrocyclone density regime on a closed circuit grinding system to the circuit product quality. The majority of the research work done on hydrocyclones was made on open systems, however very little work was done on closed circuit grinding systems. As grinding is one of the most expensive steps in mineral processing it is of high economic interest to investigate the cyclones influence to the overall circuit performance. The overall performance of a grinding circuit can be altered by just changing the Apex diameter. Technical results On the technical side answers to the following points were found and qualified: Apex capacity and cyclone cone angle Achievable underflow density with varying particle size distribution Basic reaction of the grinding circuit to cyclone underflow density variation oThe influence of underflow density to the circulating load of a closed grinding circuit oThe influence of circulating load to slurry viscosity in closed circuit grinding oThe influence of underflow density to hydrocyclone D50 in closed circuit grinding oThe influence of underflow density to the overflow product quality in closed circuit grinding oThe content of misplaces particles with decreasing apex diameter. Recovery curve shapes and cyclone simulation For the complete evaluation of the recovery curve also the upper and the lower ends have to be looked at. Cyclone performance simulation is split into two different disciplines which is the establishing of the cyclone D50 and the realistic modelling of the shape of the estimated recovery curve which is done today with the Lynch Rao equation.The resulting curve is symmetrical around the D50 point. The upper and lower tails of this model are symmetrical and cannot be shaped differently. Systematic test work, as well as plant data, show that the shape of the upper and the lower tail of the recovery curve vary significantly with the variation of the water split in the hydrocyclone. To mitigate the shortcomings of the symmetrical approach, an improved equation for the modelling of the recovery curve is needed to provide the possibility to modify the shape of the upper and the lower tail of the recovery curve independently to adjust for varying water splits, but at the same time the approximated linear shape around the D50 should be maintained. A perfect fit with real data was found with a modified equation which is called weighted two parameter Lynch-Rao function. This weighted two parameter Lynch-Rao function is now much more suitable to describe the partition curve of a hydrocyclone under varying water splits. It is suitable for both, simulating and analyzing hydrocyclone performance more precisely as when using the symmetrical model. Economical results All operational and strategic efforts must strive towards the achievement of best operating practices as these directly translate to cash flow. The most important step to best practices is proper knowledge management and the understanding, recognizing, and growth of a firms’ intellectual capital. Two main technical approaches can be made on hydrocyclone economics. First the reduction of operating pressure which leads to savings in energy and maintenance cost. Second improved density regimes lead to improved separation and grinding circuit performance. •Improved recovery results in more product and enhanced revenues •Higher recovery leads to better utilization of exhaustible, non-renewable resources and thus increases the amount of recoverable reserves on a company, national and global level •Lower power requirements result in a reduction of operating costs leading to higher profits at given revenues •Lower power requirements result in a reduction of power-related environmental effects, notably CO2-emissions

KW - Mineral Processing

KW - Hydrozyclones

KW - Classification

KW - closed circuit grinding

KW - Aufbereitung

KW - Hydrozyklon

KW - Mahlkreislauf

KW - Klassierung

M3 - Doctoral Thesis

ER -