Project Status: Complete
Project Participants: University of Queensland
Project Leader: Nenad Djordjevic (University of Queensland)
The grain size distribution of a mineral within an ore body determines to a large extent the ease with which the mineral can be liberated – large grains are liberated at comparatively large particle sizes. Prior experimental results and literature reviews have demonstrated that coarse particle liberation is a function of the geological and structural properties of the rock, as well as the methods of blasting and rock crushing. Coarse liberation prevents having to put all rock through fine grinding and flotation separation, which has multiple environmental and economic benefits – in particular lower energy, water and reagent requirements and avoiding unnecessary exposure of unwanted components (for example sulfur bearing material that could oxidise and create liabilities from acid rock drainage).
This project aimed to evaluate and quantify coarse particle liberation for ores from the mines of the participating companies, and to determine blasting and separation/screening parameters which are likely to maximise coarse particle liberation of the valuable minerals. The project adapted and developed appropriate methods to assess the degree/effectiveness of coarse liberation and subsequently developed and applied a customised rock fragmentation model (using Finite Element Method code) to predict coarse liberation under different blasting and rock crushing parameters. The project also sought to identify and evaluate the effectiveness of alternative separation methods to separate ore from gangue at coarse particle size.
The results from the project indicate that depending on the textural features and mechanical properties of the ore, as well as blast variables (e.g. mass of explosive per hole, blast hole placement etc) it is possible to produce an ore fragment size distribution to optimise coarse liberation.