Development of a correlation between mineralogy, rock strength measures, and breakage of Copper Porphyries

Abstract

The role of the comminution step in mineral processing is to reduce the size of the ore so that the valuable minerals liberated from the gangue minerals, in preparation for beneficiation. The effectiveness of the comminution step is related to the rock strength, which controlled by the minerals making up the rock, relative mineral abundances, texture, fracture frequency, and its associations. Copper porphyry deposits account for approximately two-thirds of global copper and form a good basis for investigating the effects of ore structure in comminution.Recent developments in integrated studies between ore variability and mineral processing have driven the need to understand ore variability better as a means of maximizing the value from the ore. As a result, the developed methodologies are now being adapted for incorporation into geological and metallurgical databases, with the aim of linking ore mineralogy to comminution and beneficiation performance. However, the current developments are driven by statistical correlations rather than a fundamental and mechanistic understanding.This thesis aims to develop a fundamental mechanistic relationship between mineralogy, hardness, and breakage by focusing on proportional mineral ratio changes caused during copper ore formation. Incorporated geological understanding of porphyry copper ore formation and phyllic alteration to processing is studied for two case studies viz. Highland Valley Copper Mine (HVC) and Los Bronces Mine (LB) and the approach underpins and strengthens the current methodologies for predicting the mill throughput of copper porphyries.This new approach introduces the key ore-forming parameters to mineral processing. The relationship between processing performance (breakage) and the degree of phyllic alteration is studied. This provides a link of ore genesis with rock strength and breakage behavior. A mechanistic method of single impact load cell test was utilized to measure the rock strength. The link between the strength and primary geological features is studied using QXRD; X-ray computed tomography and automated logging instruments.The thesis establishes that there is a relationship between the proposed porphyry copper process alternation index (PAI) and rock strength. The methods in this study can be used in developing the relationships between primary geological features and the rock strength; providing a novel and powerful technique to propagate breakage characteristics into the geological model of an ore body. Barış Gazanfer Yıldırım ii Declaration by authorThis thesis is composed of my original work and contains no material previously published or written by another person except where due reference has been made in the text. I have clearly stated the contribution by others to jointly-authored works that I have included in my thesis.I have clearly stated the contribution of others to my thesis as a whole, including statistical assistance, survey design, data analysis, significant technical procedures, professional editorial advice, and a...

The interrelation of petrographical propeties of rocks and their crushing and grindig features : A literature review

“…It is a method suited for the definition of porosity, fracturing, cavities and their distribution by diameter, volume, sphericity degree and microtomography can be applied in the measurement of mineral phases with equal X-ray density throughout the whole sample. The method uses an X-ray beam signal that is a function of the incident X-ray energy and the linear attenuation coefficient, which is proportional to the mean local density of the particle [4]. During scanning the sample is rotated around a vertical axis by 180° with certain steps.…”

“…Wills and Napier-Munn [9], Hilde and Powell [10] defines texture as the mineralogical composition, grain size and size distribution, grain shape and orientation, shape distribution, irregularity of the grain boundaries, spatial distribution of the grains, and associations between minerals. Petruk [11], Yildirim [4], Dominy [12] complements this with the grain boundary relationships, fractures and veinlets. Popov et al [2] differentiate rock texture and structure.…”

“…The energy consumed in the process of comminution depends on both the mechanism of comminution and the mechanical properties of the materials being ground [2]. Energy consumption during crushing is related to the rock strength, which is controlled by the constituent minerals of the rock, relative mineral abundances, texture, fracture frequency, and its associations [3,4]. The effect of rock properties like mineralogy, texture and structure on the grindability and crushability is a widely researched topic in the international literature.…”

Selective breakage of mineralised particles by high voltage pulses

“…Chile. The deposit is hosted mainly in two phases: the Rio Blanco Granodiorite (GDRB) and the Cascada Granodiorite (GDCC) (Frikken, 2003;Yildirim, 2016). The GDRB is characterised by a coarser grain size, and a greater abundance of orthoclase feldspar and plagioclase with albiteandesine compositions (see Figure 3.2, first pile on the left) compared to the GDCC.…”

“…The GDRB is characterised by a coarser grain size, and a greater abundance of orthoclase feldspar and plagioclase with albiteandesine compositions (see Figure 3.2, first pile on the left) compared to the GDCC. The GDCC has a finer grain-size and is enriched in Ca-plagioclase (Yildirim, 2016) (see The main commodities of Sample F are Cu and molybdenum. However, molybdenum is not found in the as-received sample in this case study and is therefore not concerned.…”