A study of the applications and modelling of high voltage pulse comminution for mineral ores

Abstract

The pre-treatment of ore particles by high voltage pulses (HVP) at low specific energy has a potential to reduce the energy consumption and operation costs. Nevertheless, the influencing factors and the behavior of HVP breakage of ore particles have not yet been fully understood. The overall objective of this thesis is to study the applications and modelling of HVP breakage by understanding the behaviour of ore particles subjected to pulse discharge. The three areas investigated are:1)The effects of mineral properties on HVP selective breakage and the application of this selective breakage in ore pre-concentration.2) The methods to evaluate and to characterize HVP breakage results. 3)Modelling ore particle behavior in HVP breakage.In this project, the selectivity of HVP breakage is studied using synthetic samples made of construction grout and pyrite grains. The result confirms that the breakage response of particles is dominated by the locality of electrical breakdown channel. The electrical breakdown channel locality is controlled by the grains of minerals with high conductivity/permittivity and their location in a particle. This understanding has led to the discovery of a novel technique for ore preconcentration using high voltage electrical pulses. The technique utilises metalliferous graininduced selective breakage, under a controlled pulse energy loading, and size-based screening to separate the feed ore into two products for splitting of ores by grade.To evaluate HVP breakage results, a t 10 -based model was developed to predict the degree of impact breakage, t 10 , of pulse-treated particles from that of untreated particles. This model incorporates only one parameter, C Ab , which is equivalent to percentage change of A×b values. The t 10 -based model can be used to assess energy reduction due to the pre-weakening effect in the downstream mechanical comminution process. A Wide-size JKRBT characterisation method was created, initially for quick determination of breakage characteristics of the HVP product; ultimately for use as an express ore breakage characterisation method. In this method, particles in wide size range are tested as one size class in the JKRBT by single-particle breakage mode, significantly simplifying the feed particles preparing and product sizing procedures. A conceptual design of an on-line ore ii competence measuring system based on this principle is proposed. Both the t10-based model and the Wide-size JKRBT method utilise a size-dependent breakage model previously developed by the JKMRC.Behaviour of ore particles in HVP breakage was investigated with a pilot scale and a laboratory scale HVP breakage devices. The effects of specific energy, pulse voltage, cumulative discharges, feed particle size and ore particle breakage pattern (body breakage or surface breakage) were investigated. Based on the data, a model structure for HVP breakage was developed, which incorporates four sub-models using the similar structure to predict four HVP breakage indices: body breakage probability...

Pilot-scale investigation of two Electric Pulse Fragmentation (EPF) approaches for the mineral processing of a low-grade cassiterite schist ore

“…This total energy input is then divided by the mass of material to give a discharged energy value in kWh/t. More information on the calculation of the JPP can be found in Zuo (2015) .…”

Simulating electropulse fracture of granitic rock

“…Moreover, such treatments are capable of enabling new hard-rock processing methodologies: improving mining eciencies by allowing faster, more precise cutting operations in-place of slower drill & blast mining; and providing remediation for geothermal wells via slotting and cavity formation. As a result, high voltage pulses have also been used for drilling and mining applications [4,5,6,7,8], and in civil engineering demolition and recycling operations [9,3,10]. The e↵ect of high voltages on rock is also of interest in the study of fulgurites -rock formations produced as a result of lightning strikes [11].…”

Evaluation of the Alternatives for Gold Ore Grinding Circuits by Using of Laboratory Studies Results and Simulation Method; Case Study: Iranian Gold Co.

“…As noted, the existence of accurate and validated models and extensive industrial data-base has led to the increasing use of JKSimMet software by various researchers. This software was used in the many comminution plants and joint industry-university research projects such as Morrell et al (1996), , Dunne et al (2001), Nikkhah andAnderson (2001), Ergun et al (2005), Delboni et al (2006), Munoz et al (2008), Pellegrini Rosario (2010), Schwarz and Richardson (2013), Hosseinzadeh Gharehgheshlagh (2014), Shi et al (2015), Zuo (2015), Maruf Hasan (2016), Tavares and Delboni (2016), Liang et al (2016), Koch (2017), Palaniandy (2017), Hosseinzadeh Gharehgheshlagh et al (2017), Wendelin Wikedzi (2018) and etc. Some important models of this software can be summarized as table 1.…”