Muography and Its Potential Applications to Mining and Rock Engineering

Abstract

Muography is a novel imaging method using natural cosmic-ray radiation for characterising and monitoring variation in average material density in a diverse range of objects that cannot be imaged by conventional imaging techniques. Muography includes muon radiography and muon tomography. Cosmic-ray-induced muons were discovered in the 1930’s, but rapid development of both muographic techniques has only occurred in the last two decades. With this rapid development, muography has been applied or tested in many fields such as volcano imaging, archaeology, underground structure and tunnel detection, rock mass density measurements, cargo scanning, imaging of nuclear waste and reactors, and monitoring of historical buildings and the inside of blast furnaces. Although applications of muography have already touched mining and rock engineering, such applications are still rare and they are just beginning to enter the market. Based on this background, this paper aims to introduce muography into the fields of mining and rock engineering. First, the basic properties of muons are summarized briefly. Second, potential applications of muography to mining and rock engineering are described. These applications include (1) monitoring temporal changes in the average material density of fracturing and deforming rock mass; (2) detecting geological structures and isolated ore bodies or weak zones in mines; (3) detecting a reservoir or boulders during tunnelling or drifting; (4) monitoring caving bodies to search remaining ore; (5) evaluating and classifying rock masses; (6) exploring new mineral deposits in operating underground mines and their surrounding brownfields. Finally, some issues such as maximum depth muons can reach are discussed.

Reduction of Fragment Size from Mining to Mineral Processing: A Review

“…To overcome this, a physical property of the rock mass-characteristic impedance or acoustic impedance (the product of the density and the sonic velocity of the rock mass)-may play an important role, since it describes the wave reflectivity at discontinuities like joints and cracks in the rock mass (Zhang 2016a;Zhang et al 2020c, d). In particular, since the sonic velocities of rock masses can be measured in the field by a seismic system (or vibration monitors) and the densities of rock masses may be determined by muography (Zhang et al 2020c;Holma et al 2022) or a geophysical method, the impedances of rock masses can be determined and the rock masses may be evaluated. In this way, a blast design can be made using more detailed rock mass information.…”

Muography, Outreaching, and Transdisciplinarity: Toward the Golden Age of Muography

“…Based on the sheer number and content of muography-related publications in the last decade [12,13], it is hard to argue against the conclusion that muography is currently experiencing a progressive growth stage that overpasses the speed of any of its earlier growth stages. Likewise, it can be reasoned that muography is not anymore the playing field for particle physicists and detector designers alone.…”

“…Since atmospheric muons can be detected as rare particles in well over 1 km depth, it can-at least theoretically-be envisioned a future where muography is applied in relatively deep underground settings to the most diverse group of applications [12,13]. Therefore, muography demands an interdisciplinary if not transdisciplinary research approach as data inversions and interpretations are not always straightforward.…”

A Borehole Muon Telescope for Underground Muography

“…In the muographic field, using compact detectors is advantageous when one wants to carry out direct imaging of underground or buried structures [1,2,3,4,5,6,7]. Unlike Muography applied to volcanoes [8,9,10,11,12,13,14,15,16], where the use of large detectors requires installation in ad hoc structures or in any case in large natural spaces, in underground Muography, the spaces that can be used for the installation of detectors are almost always limited.…”