A mineral liberation study of grain boundary fracture based on measurements of the surface exposure after milling

• Published in: International journal of mineral processing Vol. 156; pp. 3 - 13
• Main Authors: Leißner, T., Hoang, D.H., Rudolph, M., Heinig, T., Bachmann, K., Gutzmer, J., Schubert, H., Peuker, U.A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 10-11-2016
• Subjects: Exposure; Fracture mechanics; Grain boundary fracture; Grain size; Intergranular fracture; Mineral liberation analysis; Minerals; Parameters; Phase boundaries; Phase transformations; Preferential breakage; Random fracture; Specific surface; Transgranular fracture; Mineral liberation analysis; Preferential breakage; Transgranular fracture; Random fracture; Grain boundary fracture; Intergranular fracture
• ISSN: 0301-7516; 1879-3525
• DOI: 10.1016/j.minpro.2016.08.014

Minerals can be liberated by random fracture of particles into smaller fragments or by detachment along phase boundaries. These two mechanisms represent borderline cases. When ores get comminuted the liberation of minerals is achieved to some extent by both mechanisms. This article describes a method to determine the extent of transgranular and intergranular fracture based on 2-dimensional analysis of surface exposure of minerals.
The approach uses the unbiased surface information of phase specific surface area (PSSA), phase specific free surface (PSFS) and phase specific interfacial area (PSIA) of minerals and their change with comminution. The parameters are discussed related to the normalized grain size, which is the ratio of mineral grain size in the product to mineral grain size in the unbroken material. Finally, the amount of transgranular and intergranular fracture on surface exposure can be calculated using the phase specific surface parameters.
A sedimentary rock (apatite ore), an igneous rock (nepheline-syenite) and an artificial material (copper slags) were ground to different fineness. Based on the mineral liberation analysis (MLA) of feed and products, the extent of phase boundary fracture on the surface exposure of the minerals is studied.
•Grain boundary fracture was studied using MLA.•The amount of intergranular and transgranular fracture after grinding was measured.•The evolution of the percentage of detachment on liberation was studied with particle size.•Different fracture and liberation characteristics are shown on 3 different materials.