Prof. David Williams is a leading expert in mine waste management and mine closure. (Photo: David Williams)
As his 40-year teaching tenure at the University of Queensland draws to a close, Professor David Williams reflects on the important lessons he has learned
By Carly Leonida, European Editor
I first met Professor David Williams in 2019 in the wake of the Brumadinho tailings dam disaster. In the days following the news of the breach, I decided to write an article that went back to basics and examined fundamental best practices in tailings dam design and construction.
A mutual friend put us in touch and, at a time when few professionals felt ready to speak out, Williams not only rose to the challenge, lending his deep expertise and opinions to the article, he also rallied a global network of engineering professionals to do the same. The resulting article was a valuable resource, and we went on to collaborate on a further article for Engineering & Mining Journal in 2020.
When Williams’ former PhD student, Dr. Danish Kazmi, contacted me to say that Williams was retiring from teaching (although he will continue as Emeritus Professor at the University of Queensland and will remain active in high-level consulting), I jumped at the chance to interview him again, this time with a more personal slant.
As Director of the Geotechnical Engineering Centre at UQ, Williams has over 40 years of teaching and research under his belt, has authored over 300 research publications, and is Manager of the industry-funded Large Open Pit Project. In 2020, Williams initiated and first delivered AusIMM’s Professional Certificate in Tailings Management – a course that has now been delivered to over 900 tailings professionals. He is also an active industry consultant and sits on numerous technical review boards for some of the world’s largest tailings dams.
“My career highlights are all to do with the people I have and continue to interact with, the many students, university and professional colleagues and mining clients,” he told me. “I value most the many opportunities that I’ve had to mentor the current and next generation of geotechnical engineering professionals.
“My teaching has focused on encouraging students to think critically and add value, not merely to put numbers in an equation. The mark of an expert, in my view, is one who can explain his or her expertise in terms that any audience can understand and relate to.”
Williams’ career journey started with, what he describes as “a process of elimination” during his years at secondary school.
“I talked with a number of professionals, including Alan Longworth of consulting company, GHD, in my hometown of Melbourne, and quickly settled on pursuing a degree in civil engineering at Monash University,” he told me. “During my degree, I specialized in soil mechanics, inspired by the late Associate Professor, Ian Donald. I was also a cadet engineer with the then Country Roads Board (CRB) of Victoria.”
The cadetship obligated Williams to work for the CRB for five years after graduation, though he quickly gravitated towards a PhD in soil mechanics.
Williams said. “I joined Churchill College at Cambridge University in the UK and studied under Dr. Dick Parry, specializing in piling research. I then returned to Melbourne and briefly to the CRB before joining Golder Associates, first in Melbourne and then in Brisbane.”
Williams’ work with Golder saw the start of his involvement in the geotechnics of mine waste, which continued when he joined UQ in 1983, and where he has now spent 41 years.
Lessons in Managing Mine Wastes
“What key changes have you seen in mine waste management and mine closure during this time?” I asked.
“The two key challenges are consistently net present value (NPV) accounting being used as a key driver of decision-making, and the human failing of continuing to do the same as we have always done, expecting or hoping for a different and better outcome,” Williams replied frankly.
“Mine wastes continue to be seen as merely a ‘cost’ to be minimized. In fact, it’s as inevitable a cost as mining and processing, on which the mining industry bases key performance indicators (KPIs) and bonuses. Mining companies are actually in the waste business, and increasingly so as ore grades continue to drop and mines continue to extend ever deeper. Poor mine waste management risks failures, with consequent loss of life, injury, and damage to infrastructure and the environment, and escalates mine closure costs. Failures threaten the mining industry’s financial and social licences to operate, and its ability to control its activities.”
He explained that leading mine waste management focused on eventual closure minimizes the whole-of-life cost and better ensures safe, stable and non-polluting mine waste facilities in perpetuity. This approach could restore the mining industry’s financial and social licences to operate, and to supply the commodities that have become essential to sustaining modern life.
“This realization is slowly growing, with greater focus now being placed on improved mine waste management and the closure of mine waste storages,” he said.
“And how would you like to see these disciplines evolve over the next 40 years?” I asked.
“The mining industry is overly siloed, and in need of a more holistic and multi-disciplinary approach,” Williams replied. “This would help to better inform the global community of the importance of mining and of the management and closure of the increasing amounts of wastes produced as lower-grade orebodies are exploited.
“Mining is a waste business, which must be better managed. The industry can no longer ignore or hope to dodge criticism in the mistaken belief that only poor operators will be penalized. In fact, the worst operator tarnishes the whole industry. The mining industry must improve its management of mine wastes and showcase this effectively, to counter all the negative sentiment about it.”
He added that reprocessing and the reuse of mine wastes to add value must be given more prominence.
“Today’s mine for a given commodity can become the future mine for other scarce resources, such as construction sand (the second most used resource after water),” said Williams. “The whole of life must be considered, involving mining, processing, waste storage, reprocessing and reuse. Each phase should optimize the next.”
Making Tailings Storage Safer
Williams was a member of the expert panel that investigated the technical causes of the Brumadinho tailings dam failure, and he sits on tailings independent technical review boards for numerous operations and major mining companies worldwide, including Escondida in Chile. He also authored the 2009 and 2016 editions of the Tailings Management Handbook. So naturally, I had to ask: “how can operators make tailings dams safer?”
“The rate and consequences of tailings dam failures continue to be unacceptably high,” Williams told me. “The key to making tailings dams safer is to separate the safe, stable and non-polluting ‘containment’ of tailings in perpetuity from their ‘storage.’”
Dewatering tailings to minimize their required storage volume minimizes the height and, hence, the cost of containment. Williams believes that satisfying these aims would make the expected goal of designing for closure a reality.
“There’s a need to move away from the way we have always managed tailings, sometimes poorly, towards leading tailings management, with the aspirational goal of the 2020 Global Industry Standard on Tailings Management of zero harm to people and the environment,” he added.
Of course, responsible tailings management is only one facet of modern mining. Williams pointed to the industry’s public image as another important challenge that needs to be tackled collectively.
“It’s not difficult to see examples of poorly managed mining operations in any country, and there are very few well-closed mining operations,” Williams said. “This is depriving the mining industry of skilled professionals who would help to turn this around. Few aspire to work in this industry, and yet we all increasingly depend on and aspire to what it produces.”
Further, orebody grades are diminishing as demand for commodities continues to rise, and Williams added that, while the drive to lower (or zero) carbon emissions is commendable, currently this is largely being achieved by offsets.
“The energy required remains the ‘elephant in the room’ in the drive to alternative energy sources, renewables, and critical minerals,” he told me. “It takes energy to produce the technologies needed to generate hydro, solar, wind, and wave energy. It also takes energy to create and drive electric vehicles, and it takes energy to convert water to hydrogen gas. None of these conversions are particularly efficient, and renewable energy devices are expensive and difficult to recycle, and generally end up in landfills, requiring further resources and energy to replace them.”
“A great mentor produces future leaders. David’s knowledge leadership in mine waste management and geotechnical engineering inspires his students and colleagues to become brands in their niche areas. His mentoring encourages disruptive and critical thinking, value-adding, integrity as a professional, and kindness as a human,” Dr. Danish Kazmi, on Prof. Williams. (Photo: David Williams)
Mining for the Next Generation
“Are there any emerging trends or technologies that you think could be transformational in mining on the road to 2050?” I wondered.
Williams replied: “As large open pits become too deep to be economically mined, there will be a shift to underground mining, particularly large-scale block caves. There may be a shift to mining below the oceans, and possibly beneath the North and South poles. There will also be a shift to heap leaching (by chemicals and bacteria) of crushed low-grade orebodies, which would reduce the need to grind ores, saving high grinding costs and reducing the production of tailings. Later, there will be in situ leaching within the orebody underground.
“Tailings will have to be better managed to achieve permitting of new facilities, particularly on the surface. I predict there will be even more storage of tailings in completed open pits and underground mines as existing surface tailings storages are filled and permits for new surface storages are refused.”
Last question: “Do you have any closing thoughts or nuggets of advice that you’d like to leave for our readers, many of whom are practicing professionals themselves?” I asked.
“As professional engineers and technologists, think critically and seek to add value,” said Williams sagely. “We are all ‘greenies’ at heart. Bring that mindset to the mining industry, particularly in relation to managing and closing mine waste facilities. Finally, promote what is being done well by the mining industry.”
