Modeling and simulation of mineral liberation and their application on printed circuit board recycling process

초록

The two fundamental processes of mineral processing are liberation and concentration of valuable minerals. Being prior to another, the liberation of desired matter leads the efficiency of subsequent physical separation to higher level. In this point of view, in-depth study on mineral liberation is of importance in order for better understanding of not only crushing and grinding process but also mineral processing itself. In this study, a mineral liberation model for ore comminution process was introduced. The model consists of particle generation stage and comminution stage, introducing three particular concepts of liberation phenomena: 1) the ratio of unit grain size to parent particle size, 2) selective grinding of mineral components and 3) wide grain boundary. Firstly, the simple 1 dimensional liberation model for bicomponent mineral was investigated with numerical simulation, varying mineral assay, parent particle sizes and the three concepts which are mentioned above. Following the 1D-bicomponent model study, the multidimensional-multicomponent liberation model and simulation were examined. In addition to the liberation model investigation, model application to printed circuit board recycling process was conducted. Printed circuit board consists of copper laminate and glassfiber reinforced epoxy resin. The two materials have quite different physical characteristics such as grindability, density to name a few. These dissimilar properties of the two PCB components result in unique crushing and grinding behavior of PCB. The developed liberation model was induced to represent the grinding behavior of PCB. The distinct grinding phenomena, especially the grindability differences between two particles and high degree of liberation at the coarse sizes, compared to natural ores, was explicated along with the simulation results.

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