UBC Theses and Dissertations

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UBC Theses and Dissertations

Improving operation and performance of Continuous Variable Discharge concentrator Sakuhuni, Givemore


Continuous discharge centrifugal concentrators have been in use for more than 20 years but their technological advantages have not yet been fully exploited due to limited fundamental understanding of the technology and lack of operating strategy to efficiently adjust the multiple interacting variables to improve performance. In addition there is no mechanism for scale up and the existing laboratory procedures have limitations for predicting metallurgical response. This thesis focuses on two main goals. Firstly to develop a gravity amenability laboratory scale test procedure and secondly to develop a procedure for tuning CVD variables to improve operational performance with the aim of increasing application. A novel optimization approach, code named NNREGA, integrating artificial neural networks, regression and a genetic algorithm, was developed and tested for tuning CVD operating variables to simultaneously maximize gold recovery and grade from a polymetallic flotation tailing. An optimum operating line was generated using a Pareto genetic algorithm. Results show that the procedure provides an efficient way of exploring the design space to learn the relationship between interacting variables and outputs and is capable of predicting an improvement in CVD performance. By generating the operating curves, the procedure provides a basis for CVD scale up. It also allows for continuous improvement and can be used as part of an operating strategy with potential to integrate into machine logic control. A Gravity Release Analysis procedure, which consists of rougher, scavenger and four incremental cleaner laboratory scale Knelson concentrator stages was developed to characterize ore amenability to CVD concentration. The procedure was used to quantify gravity recoverable gold bearing sulphides in flotation tails from a massive sulphide ore and an epithermal gold vein ore. Results show good correlation between the laboratory procedure and CVD, with the laboratory procedure results forming an upper limit for the CVD. Thus, the Gravity Release Analysis procedure can be used to predict potential CVD application and to benchmark operating machines. Based on the Gravity Release Analysis procedure, a mechanism of quantifying gravity amenability and gravity kinetics, the gravity release index, was introduced. The index can be used to quantify the relative abundance of different gravity recoverable mineral species in an ore.

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