Contents lists available at ScienceDirect Minerals Engineering journal homepage: www.elsevier.com/locate/mineng Exploring the effect of the geological texture at meso and micro scale on grinding performance E. Díaz a,b, ⁎ , G. Pamparana a,b , L. Voisin a,b , W. Kracht a,b , P. Martínez b a Department of Mining Engineering, Universidad de Chile, Chile b Advanced Mining Technology Center, AMTC, Universidad de Chile, Chile ARTICLE INFO Keywords: Geological texture Grinding Comminution index Geometallurgy Mineralogy ABSTRACT Comminution indices are used to represent the grindability of a combination of minerals treated by specific processes. If two rock samples with similar values for an index are treated in the same comminution process, they are expected to have a similar behavior during grinding. However, indices are obtained assuming the breakage of homogeneous and continuous materials without considering minor scale mineral and geological textural char- acteristics. Eventual differences in the process could be related to those properties and may not be explained by comminution indices by itself. In the present study, two different copper ores samples with similar Bond Work index were used to evaluate the influence of mineralogy and geological texture at meso and micro scale in a ball grinding process at laboratory scale. Samples were characterized through geological texture analysis at micro- scale using petrographic microscopy, hyperspectral characterization, X-ray diffraction, and X-ray fluorescence. The effect of mineral properties on grinding was assessed through controlled grinding kinetics performed in a Magotteaux Mill®. Results show that the BWi allows to describe the transition between initial and final states at long grinding times, but it cannot reproduce the entire grinding kinetic, while textural properties, such as grain size and matrix-grain mineralogical composition, may be linked to P 80 variation over time and the variation of cumulative particle size distributions at different grinding times. Results suggest that geological texture may be considered as a complement to traditional grindability indices to evaluate the grinding performance. 1. Introduction Comminution theory has long been focused on the relationship between applied energy and the particle size obtained from a given initial feed size (Eq. (1)), always assuming that the material is brittle. This means that there would be no energy adsorption related to pro- cesses such as elongation or contraction of materials, and therefore, the energy would be used entirely in breakage mechanisms (impact, abra- sion/shear, attrition, and compression) (Lynch, 2015). Through the years, authors Hukki (1961) have approached this problem in different ways, and as pointed, all presented versions correspond to specific forms of the same relation, but applicable to different parts of the size reduction curve. =− dE K dx x n (1) where • E: Specific energy of comminution (kWh/t) • K: Comminution constant • dx x n : Particle size variation during comminution Among most renowned approaches of the comminution theory (von Rittinger, 1867; Kick, 1885; Bond, 1952), Bond’s theory (Bond, 1952) has been the most important, due to its practical applicability to design and optimization of grinding circuits (Rowland and Kjos, 1978). To improve its accuracy, many correction factors have been added since its publication to provide a better representation of industrial perfor- mances (Rowland and Kjos, 1978), but maintaining the primary form of the original Bond’s equation (Eq. (2)) Morrell (2004). In this equation, W i represents the Bond Work Index (BWi), the most widely used para- meter to measure the ore grindability, which can be obtained from plant data or experimental standard tests (Bond, 1968). = − W W P F ( 10 10 ) i 80 80 (2) where https://doi.org/10.1016/j.mineng.2019.106032 Received 1 December 2018; Received in revised form 11 September 2019; Accepted 16 September 2019 ⁎ Corresponding author at: Universidad de Chile, Chile. E-mail address: eduardo.diaz.v@ug.uchile.cl (E. Díaz). Minerals Engineering 144 (2019) 106032 Available online 23 September 2019 0892-6875/ © 2019 Elsevier Ltd. All rights reserved. T