Simulation of Electrical and Thermal Properties of Granite under the Application of Electrical Pulses Using Equivalent Circuit Models.

Kyosuke Fukushima,Akira Otsuki,Naoko Obara,Mahmudul Kabir,Kensuke Kanda,Mayuko Fukuyama

doi:10.3390/ma15031039

Abstract

Since energy efficiency in comminution of ores is as small as 1% using a mechanical crushing process, it is highly demanded to improve its efficiency. Using electrical impulses to selectively liberate valuable minerals from ores can be a solution of this problem. In this work, we developed a simulation method using equivalent circuits of granite to better understand the crushing process with high-voltage (HV) electrical pulses. From our simulation works, we calculated the electric field distributions in granite when an electrical pulse was applied. We also calculated other associated electrical phenomena such as produced heat and temperature changes from the simulation results. A decrease in the electric field was observed in the plagioclase with high electrical conductivity and void space. This suggests that the void volume in each mineral is important in calculating the electrical properties. Our equivalent circuit models considering both the electrical conductivity and dielectric constant of a granite can more accurately represent the electrical properties of granite under HV electric pulse application. These results will help us better understand the liberation of minerals from granite by electric pulse application.

Highlights

Minerals are familiar to us in our daily lives and are used in various fields [1]
A decrease in the electric field was observed in the plagioclase with high electrical conductivity and void space
Our equivalent circuit models considering both the electrical conductivity and dielectric constant of a granite can more accurately represent the electrical properties of granite under HV electric pulse application

Summary

Introduction

Minerals are familiar to us in our daily lives and are used in various fields (e.g., ceramics, pharmaceuticals, cosmetics) [1]. In order to extract minerals from rocks, a combination of mechanical comminution methods of crushing and grinding (e.g., ball mill) based on compression, impact and shearing mechanisms are generally used [2]. The energy efficiency of these methods is as low as 1%. For hard rocks, such as granite, the mechanical grinding is inefficient due to tool wear and the increase in cost [3]. A new method for size reduction and selectively liberating minerals from rocks using high-voltage electric pulses has been developed [2]. Electric pulse liberation of minerals has been reported as a solution for low energy efficiency in comminution [6,7,8]

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Conclusion