Using mineralogical characterisation and process modelling to simulate the gravity recovery of ferrochrome fines

The recovery of ferrochrome (FeCr) alloy from fine (<600 μm) ferrochrome slag typically involves the use of gravity concentration, amongst other physical separation techniques. This study demonstrates the value of utilising mineralogical methods both to determine alloy composition and liberation and to assist in setting up partition surface models for a shaking table. A Mineral Liberation Analyser (MLA) was used to measure size, density, shape and liberation data of each alloy and mineral in a set of shaking table products. The amount of detailed data gathered by the MLA was sufficient to generate particle tracking analysis (PTA) data in order to simulate the recovery of alloy and mineral phases. Two flowsheet configurations were evaluated to ascertain the possibility of producing a high grade product (>97.5% metal content) comparing shaking table and Reflux Classifier performance. The results of this study show that an approach of using particle characterisation by MLA, coupled with surface partition modelling, may be a useful technique to model gravity separation of fine particles, especially where both valuable and gangue phases contain common elements in their composition.