Hard/stiff surface coatings for particle weakening, part I: Methodology

Size-reduction processes are essential for liberating valuable minerals yet energy-inefficient, which needs to be remedied by developing energy-efficient methods. This work is the first part of a wide study that (i) describes a surface coating method, namely, spray coating, and (ii) presents some preliminary results that hard or stiff surface coatings can be used to weaken softer ore particles. The hard surface coatings were achieved with a ceramic spray and two inorganic precipitates (CaCO3 and silica). The fracture energy and/or strength of spraycoated and uncoated particles was measured using the Short Impact Load Cell (SILC). Spray coating can only yield low surface coverage (up to 1-2% of the mass of particles), which is only apparent if particle surfaces are washed before coating. Nevertheless, the preliminary results suggest significant reductions in the fracture force and energy of soft ore particles after they are coated.