The art of rock engineering design and the need for research

Details

Created: Tuesday, 21 October 2025 11:02

Written by F. Malan

Rock Engineers and mine personnel frequently disagree on design aspects. These disagreements can lead to poor designs or failures. A number of large collapses have occurred in the bord and pillar mines and open cast mines in the Southern Africa region in the last two decades. Can we learn from the decision-making that led to these collapses and improve? Philosophy offers the opportunity to adopt a reflective learning approach.

ChatGPT gave an interesting insight into this aspect of mine design. Rock engineering is less of an exact science than other engineering disciplines and it is suggested that rock engineering design is best described as a “science-based art”. The science provides the foundation and design is based on aspects such as rock mechanics principles (e.g., stress-strain behaviour, and failure criteria), empirical methods (e.g., Q-system, and RMR), numerical modelling (e.g., finite element, distinct element, and boundary element methods), monitoring and instrumentation (e.g., extensometers and stress cells) and geological and geotechnical data (e.g., boreholes, core logging, and lab tests). The designs are never purely scientific owing to reasons such as natural variability of the rock mass, the geology is complex and discontinuous, the uncertainty caused by incomplete or generalised data, decisions must often be made with partial information, when conditions change the designs must evolve, and balancing performance, cost, and safety is not purely technical.

Based on these considerations, it implies that “industry standard” criteria for design neither are always the best technical solutions, nor does it imply these criteria are correct. Davide Elmo and his co-workers explored this topic and examined rock engineering using a philosophical approach (Elmo et al., 2022) in Examining Rock Engineering Knowledge through a Philosophical Lens. Geosciences. They noted that rock engineering designs are shaped by cognitive biases, which over time have created a dogmatic barrier to innovation. Almost no attention has been given to the impact that subjectivity, human factors, and lack of scientific replicability have on the empirical design methods used in this field.

As a complicating factor, the modelling methodologies and constitutive codes typically used are difficult to calibrate and represent a universal challenge for the application of rock engineering models. As more complex numerical models are developed for the improved simulation of observed rock mass behaviour, more onerous requirements of model calibration and user expertise are required. This applies to boundary element models, finite element, and finite difference codes. Elmo et al. (2022) made the following important observation: “It is evident generally that if older and simpler solutions have a clear advantage in terms of durability and/or efficiency, even if this advantage is restricted to a limited purpose, they continue to exist and evolve.” In his 2003 Presidential Address: Rock engineering – good design or good judgement, T.R. Stacey recognised this problem and noted that rock masses are so complex that realistic modelling, even with sophisticated methods, is impossible. Simple elastic models with good engineering judgement may therefore continue to exist as one of the practical rock engineering tools.

As a first step to mitigate the uncertainty in rock engineering and the challenge described in this note, Elmo et al. (2022) emphasised that for research, critical thinking needs to be applied and the foundations of rock engineering as an empirical science should be questioned. Furthermore “replication” research should be conducted as a more rigorous form of review compared to the traditional peer review. A recent example of replication research is given by the Le Roux and Malan paper (2024). Researchers need to provide full information to allow others to replicate their work. Very often the assumptions used for numerical modelling of layout design are not given in design reports and these need to be included in the reports.

F. Malan

Safety and the human dimension

Details

Created: Thursday, 02 October 2025 09:08

Written by M. Onifade

Mining has historically been one of the most hazardous industries, a reality that has shaped the sector’s reputation for high risks and low margins of safety. Despite decades of progress in mechanisation, automation, improved ventilation, and the widespread adoption of personal protective equipment, accidents and occupational diseases remain serious and persistent concerns. Underground mining poses unique challenges because workers are confined to narrow spaces where they are exposed to unpredictable geological conditions, poor visibility, high temperatures, and dangerous gases. Beyond these acute risks are chronic health conditions that develop over time, including silicosis from prolonged inhalation of respirable dust, occupational hearing loss from exposure to high levels of noise, and musculoskeletal disorders resulting from heavy manual handling. The persistence of these problems highlights the complexity of mining safety and health, showing that technological improvements alone cannot eliminate them.

What is particularly striking is that many of these hazards are not new. Historical records show that mine heat stress, for instance, was a well-recognised occupational hazard in South African gold mines by the mid-twentieth century, where deep-level mining exposed workers to extreme geothermal heat. Decades later, despite significant research into mine cooling systems, refrigeration, and ventilation optimisation, heat stress remains a major challenge in ultra-deep mines worldwide. Likewise, dust-related diseases such as silicosis and pneumoconiosis were documented as early as the nineteenth century, yet miners in jurisdictions with strict regulation, including Australia and the United States, continue to suffer from such conditions. In some coal mining regions, cases of “black lung” have even re-emerged after being thought nearly eradicated. This persistence suggests that while engineering controls and medical surveillance programmes are critical, they cannot succeed without rigorous enforcement of standards, strong occupational health policies, and most importantly, a cultural commitment to safety.

Indeed, the evidence shows that accidents and diseases in mining often result from organisational and systemic failures as much as from technical limitations. For example, lapses in enforcement, inadequate training, or production pressures can undermine the effectiveness of safety measures. Worker participation is therefore vital; miners must not only be protected by technology but also empowered to identify risks, report unsafe practices, and influence decision-making without fear of reprisal. A culture of safety must be nurtured at every level, from corporate leadership down to the underground face worker. Without this cultural shift, even the most advanced safety systems risk becoming superficial or poorly implemented.

The rise of automation and digital technologies in mining presents a new chapter in this long struggle between hazard and safety. On one hand, the deployment of autonomous haulage systems, remote-controlled drilling equipment, and advanced real-time monitoring systems offers unprecedented opportunities to remove workers from high-risk zones. Technologies such as wearable sensors can track miner fatigue, monitor gas levels, and even detect hazardous movements, thereby reducing accidents. Drones and robotic inspection devices can be sent into dangerous areas before humans, minimising exposure to unknown risks. These developments, if integrated with strong safety systems, have the potential to revolutionise mining health and safety.

On the other hand, these same technologies introduce new challenges. Automation can displace traditional jobs, leading to unemployment or underemployment in mining-dependent communities. The shift toward digital mining requires new skill sets, including expertise in programming, data analysis, and systems management, which many mining regions, especially in developing countries, are not equipped to provide. Without adequate reskilling programmes and community investment, technological advances may exacerbate social inequality, leaving behind the very workers they were meant to protect. Furthermore, automation can introduce new categories of risks, such as cybersecurity vulnerabilities in mine control systems or over-reliance on complex technologies that can fail under certain conditions.

Safety in mining, therefore, cannot be considered in isolation from broader social justice concerns. Protecting workers underground must go hand-in-hand with protecting the wellbeing of mining communities on the surface. Social sustainability to ensure that workers have meaningful employment, access to healthcare, education, and economic opportunities remains central to the true advancement of mining safety. Ultimately, while technology can reduce exposure to hazards, it is strong regulatory enforcement, cultural transformation, and inclusive community engagement that will determine whether the mining industry can overcome its long history of danger and fulfill its responsibility to both workers and society.

M. Onifade

Complexity of Slope Stability

Details

Created: Thursday, 28 August 2025 15:13

Written by R. Armstrong

The South African mining industry is well known for the advancements in underground, especially ultra-deep, mines. But it has also made significant contributions to open pit mining and the stability of slopes. The SAIMM hosted a symposium on slope stability as early as 1970 (book S2 in the symposium series), which was conceptualised by the SAIMM because open pit mines were getting bigger and deeper, and the sharing of knowledge and experience from the industry was required. Over 300 local and international delegates attended the symposium, including technical, industry, and academic leaders in open pit mining and rock mechanics.

Incidentally, two of the speakers would go on to found two international mining consulting firms. Again, recognising that pits were being planned much deeper than ever before, The SAIMM planned the first International Symposium on Stability of Rock Slopes in Open Pit Mining and Civil Engineering in 2006, which has since been held 10 times in 8 different countries (now informally referred to as simply The Slopes Conference). This symposium was again organised by the SAIMM in 2015. This special edition of the journal serves as a further commitment to the development of the science and engineering of rock slopes, with the very high response of papers dealing with some interesting and pertinent developments. Topics covered include: slope stability analyses, groundwater interactions with slopes, forecasting of failure, detection of underground cavities, and the back analysis of a very large slope failure.

Significant developments have taken place in the last two decades in monitoring and numerical modelling of rock slopes. These often overshadow the importance of understanding the actual mechanics of big slopes, and how to reliably design them. Many advances in technology have provided the tools to aid in this, but there is a long way to go in understanding the complex interplay of the geological complexity (including varying rock types, geological structure, alteration, and weathering), complex groundwater systems (often grossly over simplified), strength properties, appropriate failure criteria, slope geometries, blasting, et al. These complexities are impossible to include in any single analysis or model, so the design and understanding of large slope behaviour still require contextualising multiple over-simplified models and determining how their interaction results in the limitation of slope equilibrium. Furthermore, how to manage all of that in the implementation of big slopes. This complexity means that slopes require the inputs from many specialists and an understanding of the limitations of their science and models. So much more is needed in the development of rock slope engineering.

R. Armstrong

Finding the needle in the haystack

Details

Created: Thursday, 24 July 2025 07:14

Written by Q.G. Reynolds

In the course of our engineering work on mining and metallurgical plants we are often called upon to evaluate the merits of different choices in process flowsheets, operating parameters and philosophies, raw material selection, and many others. The phenomenological complexity of the minerals industry usually means that each of these aspects is parameterised by a large number of variables, and there are also strong coupling effects between them – one changes a feed-rate setting here, and even though it fixes the immediate production problem over here, it also affects several other things over there in ways that one did not expect.

In the digital age we have access to powerful process and systems models, which can create virtual analogues (or “digital twins” if one prefers catchy jargon) of our real-world plants, which can make decision-making easier. However, in the pursuit of improved accuracy these models often start to become as impenetrable and confusing a black box as the actual thing they are trying to simulate. This is especially true when data-centric artificial intelligence and machine learning methods are included in the mix. Manually exploring such systems models by making basic changes using oversimplified fundamental principles, can very quickly turn into an endless game of whack-a-mole to mitigate the cascade of unintended consequences.

To better manage this problem, two formal mathematical concepts are becoming increasingly useful as interface layers over complex systems models. Uncertainty quantification tracks the propagation of errors through a system from inputs to outputs, and sensitivity analysis identifies how strongly outputs are affected by changes in the inputs. In combination, these tools can help guide design or process optimisation studies to find small changes that yield large improvements while minimising undesirable side effects. They are well worth investigating to help us find the needles in our metallurgical haystacks.

Q.G. Reynolds

The value of good mentorship

Details

Created: Thursday, 26 June 2025 06:40

Written by P.H. Radcliffe

Just a couple of years ago the outgoing Chairman of the SAIMM Editorial Board, Dave Tudor, suggested that, as a previous metallurgical colleague, I should join the Board. Although I have been a member of the Institute for many years and was a previous Chairman of the Free State Branch, my knowledge of the management of the Institute was limited to attending some excellent schools and studying relevant journal papers.

After attending several Editorial Board meetings, I have come to appreciate the Board’s and the Institute’s dedication in putting together a world-class journal. As a retired engineer, designer, and operator of metallurgical processing plants, I have now come to admire the knowledge and hard work that my recently acquainted Editorial Board colleagues, both academic and industrial, consistently put in.

At a recent Board meeting the subject of publishing student papers was raised, which reminded me of the commitment of my former mining house to the development of future metallurgical management, which started at school level with identifying students capable of the required matric results to succeed with metallurgical or chemical engineering degrees or higher national diplomas. In addition to local mentoring and coaching when graduates were employed by a mine, a panel managed by the Technical Director’s office interviewed metallurgists regularly to discuss wider group opportunities. My most memorable interview was during the commissioning of a particularly difficult plant, when I was told some home truths and reminded of the importance of the success of that project with specific reference to my future career! To this day I am thankful to the panel for their straight talk.

Which brings me back to the subject of student papers and indeed other papers that have a topic of relevance to journal readers, but which still need further input to raise them to the standard required by the journal. It is surely the responsibility of academics to coach their students in presenting promising papers to this Institute and others for review. Such mentoring is important not only for the development of such young people at the start of their professional lives but also for the submission of important papers that such young engineers may yet write in the course of their future careers.

The selection of peer reviewers for all papers submitted to the Institute is a challenging duty and arguably the most important task undertaken by the Editorial Board. It is in this context that the levels of written texts and graphic portrayals, the standards of referencing of previous work, the degree of clarity and accuracy of data presentation, and ultimately the significance of the interpretations and the originality of the data acquired, are judged in terms of the degree of advancement of science and technology in the relevant mining, minerals, and metallurgical fields.
When successfully published, a paper may be considered a significant achievement and a feather in the author’s cap, albeit a team effort on the part of the reviewers, the editor, the Board’s editorial staff, professional proofreaders, and finally, the author.

The need to maintain standards for all papers published in the Journal is of vital concern as this is required in order to retain the internationally accredited standing of this Institute’s journal. Such matters also reflect in the overall numerical grading of all scientific and technical journals, as portrayed by various numerical systems, including the impact factor and other such evaluation tools. The grading of a journal and the papers it publishes impacts, in turn, on the monetary value for which academics are financially and academically rewarded. And so, the relevance of mentoring to achieve the production and publication of valuable papers has meanings way beyond that simply of a grammatically correct text.
I am glad to say that mentorship from supervising academics for young student authors is generally the case. I was pleasantly surprised recently to have sight of a student paper, which ‘ticked all the boxes’ such as relevance, originality, and presentation. Someone, somewhere in our double-blind reviewing process was mentoring splendidly! May this be the case for many more young authors, as it is these young people that will evolve into mature authors of the future and hence, the source of excellent papers for this and other journals, and the scientific and engineering communities they serve.

P.H. Radcliffe

Think small

Details

Created: Tuesday, 27 May 2025 11:49

Written by D. Vogt

Mining is big business. For many commodities, the orebodies are big and the best way to exploit them for maximum profit is on a large scale.

But do large mines mean large equipment? At the moment, the answer is yes. Ramps can only handle a limited number of trucks per day and removing that obstacle is very expensive; more or wider ramps, a larger pit to hold them, and a lower extraction ratio. We deal with the problem of optimising ramps by making our trucks as large as possible. This also means we can manage with fewer drivers and, as is common knowledge, drivers are an ongoing expense.

If we look at air travel, we have seen the same move to larger equipment over time. A route like Johannesburg to London is like a ramp. It cannot take many more aircraft than it already does, because airports are constrained to accept a limited number of aircraft per day. The limit is safety; aircraft cannot land more frequently because of fear of collision. The result is a long-term trend to larger and more fuel-efficient aircraft.

But aviation is changing. We are seeing developments in local flight like the Lilium air-taxi: electric power and vertical take-off enables quiet ‘air taxis’ that can fly directly from your house to the nearby airport, from where you can catch a plane to anywhere.

For both mine haulage and aircraft, a constraint is a driver. While aviation is becoming steadily more automated, it is unlikely that we will see pilotless planes for a while yet, more because we cannot stomach the idea of a computer flying the plane in which we sit than because it is going to be less safe. For mine haulage, we already have automated trucks, and their safety record is better than that of human-driven trucks.

In mining, it is unlikely that anyone is going to switch to many small trucks in a large operation, although there is evidence that their flexibility might make them a more cost-effective option. But then again, automating small trucks in a small operation makes sense. For example, a planned mine nearby can only work during the day, due to concerns about noise from its neighbours. In their application, a small, autonomous electric haul truck would be able to operate at night because it is silent, and in this case, would travel downhill loaded and uphill empty, and subsequently may be able to achieve its task without consuming any diesel.

With time, perhaps we will see many smaller trucks in large pits, rather than a few larger trucks, running on electricity rather than diesel, respectively. If we are serious about geometallurgy, we need to handle ore in smaller packages, and just the improvement in grade control could make the switch possible. With the widespread introduction of renewable energy, it also allows mines to lower their diesel bills and be seen to be greener.

At a time of tariffs and uncertainty, anything that can reduce risks and lower costs appears good. General automation of the mining fleet is at the point where it can solve problems and make mines at all scales more efficient, and therefore, more viable when prices collapse.

D. Vogt

Mine Closures – Past, Present and Future…

Details

Created: Thursday, 24 April 2025 05:42

Written by J. Lake

The mining industry is an exciting space, where the convergence of environmental stewardship, socio-economic responsibility, and technological innovation is reshaping the way we approach mine closure. As we navigate this complex landscape, the importance of mine closure planning is becoming more and more pronounced.

Effective mine closure begins long before the end of operations, with proactive strategies that anticipate challenges and opportunities. By embedding closure planning into the broader mine lifecycle, companies can ensure smoother transitions and more sustainable outcomes.
One of the most pressing challenges faced by the South African mining industry is the uncertainty surrounding legislation and regulatory frameworks. As governments and international bodies continue to refine their policies to address environmental and social concerns, mining companies must remain agile and proactive in their approach to compliance.

Innovation and technological advances are transforming the way we approach mine closure. From predictive modelling to advanced reclamation techniques, the integration of technologies is enabling more efficient, sustainable, and cost-effective closure solutions.

The socio-economic transition associated with mine closure is another critical focus area. As mines cease operations, the surrounding communities often face significant economic and social changes. Mines need to develop strategies for fostering resilience and sustainability in these communities, emphasising the importance of collaboration between industry, government, and local stakeholders.

The complexity of disciplines required to develop effective mine closure plans cannot be overstated. Geotechnical engineering, hydrogeology, environmental science, socio-economic planning and more, must converge to create holistic solutions.

This journal serves as a platform to explore the multifaceted challenges and opportunities inherent in mine closure, offering insights into the evolving practices and strategies that define this inevitable and critical phase of the mining lifecycle.

As you explore the articles and case studies within this journal, we invite you to reflect on the shared responsibility we have in shaping the future of mine closure. Together, through innovation, collaboration, and foresight we can navigate the complexities of this critical phase and contribute to a more sustainable and equitable mining industry.

J. Lake

Past, Present and Future Insights to be shared

Details

Created: Thursday, 03 April 2025 05:32

Written by G.R. Lane

As the incoming President of SAIMM, I have been reflecting on my 34-year career in the mining industry and the lessons I have learned; lessons I can leverage to lead SAIMM and support the industry during my tenure. Writing this month’s journal comment provides an opportunity to share part one of some of these insights.

Each role, as well as the individuals and teams I have worked with throughout my career, have shaped and expanded my experience and perspectives on how to make a difference and add value.

I began my journey as a young engineer, developing and commissioning new mining operations in Africa for a multinational mining house. Later, I pivoted to mine optimisation modelling and software development, aiming to transform mine planning as the co-founder of multiple startup businesses.

This experience reinforced my understanding of the technical and safety challenges in the mining industry, the inherent risks and variability in ore body characteristics, and the complexities of managing a dynamic, interconnected value stream of activities to mine and process ore. Additionally, a lack of management focus, caused by an overwhelming number of improvement projects and initiatives that are often poorly implemented, means that many of these efforts fail to add value.

Later in my career, after being exposed to the tools of Lean Six Sigma and the Theory of Constraints, I learned that using the right decision-making tools enables management to focus on the right leading indicators that add value. However, it would be remiss of me not to mention that none of these methodologies alone adequately address the challenges in mining. In fact, some principles of Lean can limit performance due to the inherent variability in ore and processing.

The mining industry also faces significant challenges in implementing new technology. We often underestimate the people-related challenges involved and fail to effectively design and manage the necessary changes in work processes, roles, and employee buy-in. The promises of Big Data and Industry 4.0 (IR4) are recent examples of this. In my opinion, current change management thinking and execution is not adequate for our rapidly changing future business landscape.
A common phrase I have heard over the years is: ‘Our mine is unique and more challenging, so what worked at mine XYZ won’t work here’.

To determine whether we can learn from other industries, I explored insights from the automotive sector, particularly Toyota’s leadership in systems thinking, which leverages Lean Six Sigma and a people-centric approach. The automotive industry has seen massive productivity increases over the past decade, whereas the mining industry has experienced a decline over the same period. A recording of my keynote address, ‘Has Technology Generated ROI?’, from the 2015 International MPES Conference, is available on YouTube, where I discuss these insights further.

Over the past eight years, in a new business venture, I have been able to test and refine these hypotheses across multiple industries worldwide. Whether in chocolate or biscuit manufacturing, a tissue paper mill and converting line, the production of lab-grown diamonds, product lifecycle management for high-tech equipment R&D and manufacturing, or ore moving through a value stream, the challenges remain the same. Each industry has its own technical requirements, whether in chemical engineering, metallurgy, or mining engineering, but the fundamental challenge of managing and maximizing the flow of material through a complex system of interconnected activities, as well as the impact of performance variability on this flow, is identical across industries.

What was even more revealing was that these challenges persist regardless of technological sophistication. Whether in a greenfield digital manufacturing facility equipped with expert control and real-time data reporting in dedicated operating centres or a brownfield operation reliant on paper and Excel spreadsheets for data collation and reporting, the same issues exist. In fact, we found that, in many instances, more real-time data creates more noise, uncertainty, and reactive responses to variance, leading to a further dilution of management focus – leadership time in a day is also a constraint. In many cases, general managers of production facilities spend over 75% of their time explaining yesterday’s poor performance.

In every example, production success is driven by individual effort; people working hard across all engineering disciplines and business functions, often relying on a handful of ‘heroes’ to achieve equipment reliability and production targets. One clear symptom of this is the excessive number of meetings employees at all levels attend weekly; meetings that serve no clear purpose and produce no agreed upon outcomes.

With all the technological advances in the world, we have neglected to focus on the people within this increasingly complex business system. The advent of artificial intelligence will also have a profound impact and must be designed into the future operating model.
In my next journal comment I will begin to unpack the learnings and requirements of an integrated operating model that addresses these challenges.

G.R. Lane

To act or not act (timeously), that is the question for the future

Details

Created: Wednesday, 05 March 2025 08:00

Written by A. Nengovhela

Mining has always been about more than just extracting minerals from the earth. It is about securing the future, balancing economic imperatives with environmental responsibility, technological innovation, and the well-being of those who power this industry. As we move forward, we must ask ourselves: are we truly mining with the future in mind?

The challenge of resource scarcity is real, and it is reshaping how we think about mining. The days of endless reserves are behind us, and the industry must shift from a model of extraction and export to one that embraces beneficiation, circularity, and long-term resource stewardship. The push towards a circular economy is no longer a theoretical discussion, it is a business imperative. If we fail to maximise the value of our minerals beyond extraction, we risk losing economic opportunities that could drive sustainable development across the continent.

Operational excellence remains key. New technologies are transforming mining, allowing us to extract resources with greater efficiency while reducing waste and energy consumption. But efficiency cannot come at the cost of health and safety. The risks of occupational diseases, particularly in underground mining, are well known, yet we often move too slowly in addressing them. Have we learned enough from past health crises, or are we waiting for another preventable tragedy before we take decisive action? Mining cannot afford to be reactive, it must be proactive in protecting its workforce.

The environment is another frontier where mining must do better. The industry is under greater scrutiny than ever, with water use, emissions, and rehabilitation practices facing intense public and regulatory pressure. Companies that do not prioritise sustainability will find themselves struggling to maintain their license to operate. Those that embrace environmental responsibility as a core business principle will be the ones that thrive in the years ahead.

Mining has the potential to be a driver of economic and social progress, but only if we rise to meet the challenges before us. The research in this edition highlights both the risks and the opportunities that lie ahead. It reminds us that the choices we make today will define the legacy of our industry. Will we be remembered as the generation that mined responsibly, using innovation and sustainability to build a lasting future? That is the challenge and the opportunity before us.

A. Nengovhela

Seismic activity related to mining

Details

Created: Wednesday, 12 February 2025 08:23

Written by R.J. Durrheim

This issue focuses on mine seismology, a discipline that has its roots in the South African mining industry. Gold was discovered near present-day Johannesburg in 1886. Mining related seismicity was first encountered in the early 1900s, when extensive stopes, supported solely by small reef pillars, reached depths of several hundred metres. In 1908, -the Government Mining Engineer appointed a committee to “inquire into and report on the origin and effect of the earth tremors experienced in the village of Ophirton” (Report of the 1908 Ophirton Earth Tremors Committee, Witwatersrand Earth Tremors Committee, 1915). The committee concluded that “… under the great weight of the superincumbent mass of rock [...] the pillars are severely strained; that ultimately they partly give way suddenly, and that this relief of strain produces a vibration in the rock which is transmitted to the surface in the form of a more or less severe tremor or shock.” Since then, strenuous efforts have been made to understand the phenomenon of mining induced seismicity, and to mitigate the harm that it causes through damage to mine workings and surface infrastructure, loss of production, and injury to mine workers and the public.

In recent decades, the South African mining industry has made great strides in improving safety. Every death is a tragedy. Nevertheless, we are encouraged that 2022 is the safest year on record, with 49 deaths, compared to a toll of 484 in 1994, with a similar workforce of about 500,000. Provisional figures published by the Ministry of Mineral and Petroleum Resources suggest that 2024 might be even safer. Up until 9 December 2024, 41 lives had been lost and 1746 reportable injuries had occurred, of which 12 of the deaths (29%) and 253 of the injuries (15%) were ‘rock-related’ (i.e. attributed to falls of ground and rockbursts). The rockburst risk has been reduced but not eliminated, requiring further research and better implementation of knowledge and technology. As shallow ore bodies are depleted, the depth of mining is likely to increase and it will become even more important to reduce the risk of rockbursting by managing mining-induced stresses, reinforcing excavations with robust energy-absorbing support elements and systems, and reducing the exposure of mineworkers to hazardous conditions through mechanization and automation.

Not all seismicity related to mining is bad. For example, there are techniques to destress the rock mass and reduce the likelihood of damaging events by releasing stored seismic energy at times and in places where it does not pose a risk. Furthermore, there are mining methods that depend on stress-induced fracturing to break the rock. Here it is important to monitor the progression of the cave front. Seismic energy can also be used to image the rock mass and detect new ore bodies, map extensions to existing ore bodies, and detect structures that might be seismogenic and pose risks, such as faults and dykes. Lastly, deep South African gold mines have provided the stage for pioneering scientific investigations of the physics of earthquakes, the nature of neutrinos, the characteristics of ‘extremophile’ organisms (which could be prototypes of extraterrestrial life), and even the origin of the magnetic field of the Earth and Sun.

The development of knowledge and skill in the field of mine seismology is vital for the wellbeing of the South African mining industry. The papers in this special issue record current efforts by industry practitioners and researchers to ensure that our mines remain efficient while we strive for zero harm.

R.J. Durrheim