Cave mining and deep exploration drilling are the future of the mining industry as surface orebodies become scarcer and discoveries at depth more common. Effective and efficient ways of accessing orebodies below depths of 500 m need to be a key focus for the mining industry in order to remain profitable into the future.
Mining companies, suppliers and service companies with interests in future caving methods are joining forces with Mining3 and The University of Queensland’s Sustainable Minerals Institute (SMI) to develop ‘Cave Mining 2040’. An international collaborative project aimed at developing new and improved cave mining methods, Cave Mining 2040 will focus on the future of cave mining to ensure it remains a viable, optimised and automated option that can meet future requirements efficiently, safely and cost effectively.
Potential high production rates and low operating costs mean that cave mining is increasingly the chosen method of extraction for progressively deeper large ore bodies. Despite the long lead time required ahead of an investment decision and the high capital investment required to establish a caving mine, the current cave mining techniques of block, panel and sublevel caving are presently the only viable underground mining methods that can be used to extract large, deep, lower-grade ore deposits in harsh geological and geotechnical environments.
An exhaustive list of natural geological, geothermal challenges spanning deposit depth, size, shape and more, as well as man-made challenges including ore-body access, productivity costs and others, was—after much discussion—concentrated into an outline of leading priority macro areas.
These generic priority areas are now referred to as ‘The Cave Mining 2040 Study Areas’ and form the basis of a number of collaborative industry research projects and activities with outcomes that will transform the future of cave mining.
The Cave Mining 2040 initiatives offer a historic opportunity for an industry-driven organisation to be part of the revolution of future cave mining around the world. Participating industry stakeholders are working towards an overall improvement of 25 per cent in all key cave mining processes.
The Cave Mining 2040 ‘Horizon 1 Project’ comprises eight study areas (each outlined below) likely to have immediate short to mid-term impacts on cave mining methods during the next 10 years and ultimately contribute to the overall transformation of cave mining methods.
1. Total deposit knowledge
An adequate level of orebody knowledge—including the total deposit knowledge (TDK), geological, geotechnical and hydrogeological characteristics—is the foundation upon which cave mining will be transformed in the future. The ultimate objective of TDK research is the ability to produce a 3D mining ‘uncertainty’ model of an ore deposit (that is, quantifying the key characteristics of the ore body not fully measured).
With the ability to transform geoscientific data collected during exploration into models of mining uncertainty, we can create a reliable system for the classification of minerals exploration results, and mineral resources and ore reserves according to the levels of confidence in geological knowledge within the technical and economic context. These levels of confidence will inform and guide subsequent cave mining-method selection, planning, design, construction, and operational decisions.
2. Cave Engineering
By critically reviewing rock-mass conditioning processes used in cave mining operations and other industries, such as petroleum and oil, we can potentially identify processes specific to cave mining that will improve the predictability of fragmentation, reduce the likelihood of initiating major seismicity events, and enable better forecasting of cave performance.
3. Cave Establishment
Reducing the high capital investment required to establish a caving mine requires a paradigm shift in how future deep ore deposits are accessed and caves are established. The cave establishment study area is focused on safety, speed, efficiency and reducing the up-front capital requirement.
4. Mine design for new and emerging technologies
By redesigning the extraction level arrangement to maximise ore recovery, we also enable the cost-effective use of emerging technologies and reduce the amount of required horizontal and vertical mining development, as well as ensure the effective and cost-effective implementation of automated production systems.
Because the extraction level must remain in place for an extended production period, overall layout design, ground support and roadway conditions are critical factors. By initially investing in high-performing, large-scale, lasting infrastructure, the day-to-day operational costs can be lowered throughout the life of the cave.
5. High stresses and major seismicity
Effective management of increased stresses and seismicity due to deeper cave mines is a critical challenge, and the aim of this research area is to produce a benchmark dataset capturing current industry experience related to support of access and infrastructure in deep, high-stress caves.
The ability to predict subsidence is also critical for operational hazard and environmental impact assessment. Key geotechnical and mining parameters controlling ground support performance need to be identified and practical ground support design guidelines for operating caving mines developed.
An outcome of this research will be validated design methodologies and interpretation tools for the advanced analysis of ground support performance.
6. Macro-block design and sequencing optimisation
The development of mining strategies for caving ore deposits with large footprints using the concept of macro-blocks has the potential to provide significant benefits. By taking into account in situ and induced rock-mass conditions and geological structures, while maintaining extraction level stability, macro blocks will potentially delay ingress of waste, as well as reduce up-front Capital expenditure.
7. Sublevel caving
Sublevel caving is a method often evaluated in parallel with block and/or panel caving options. It requires multiple levels of development and ongoing ring blasting for production. Sublevel caving allows for a more selective extraction but typically achieves lower production rates than block and panel caving methods.
By assessing and quantifying the interrelationship between blasting, fragmentation and gravity or disturbed flow that is available from purpose-conducted, full-scale studies we can determine methods for improving (primary) ore recovery. The research will extend or build upon ongoing work being carried out at Glencore’s Ernest Henry sublevel caving mine in north western Queensland, Australia.
8. Open Automation Platform
The development of basic open communication protocols is a subject of increasing importance in all forms of mining. Within the context of the Cave Mining 2040 Horizon 1 Project, and complementary activities in many other forums, the focus of this initiative is on the development of an open automation platform specific to cave mining, with minimum standards for interoperability. The overarching objective is to enable the effective use of different levels of automation processes and facilitate their interoperability.
Cave Mining 2040 is a cornerstone activity within the Transforming Cave Mining (TCM) initiative—a partnership between Mining3 and The University of Queensland’s Sustainable Minerals Institute to integrate and leverage cave mining capacity and capability from the two organisations and their respective networks to together build cave mining knowledge and expertise.