SUSTAINABILITY IN MINERALS: EVER MORE IMPORTANT
PROF ROBIN J BATTERHAM KERNOT PROFESSOR OF ENGINEERING THE MELBOURNE UNIVERSITY, VIC 3010 AUSTRALIA SUMMARY/ABSTRACT It is suggested that the demand for minerals and metals will increase inexorably till at least 2030 and with falling grades and rising energy and water consumption, much more needs to be done to develop a sustainable “mine of the future”. The demands for more and better sustainability are also rising, again pushing us towards the “mine of the future”. We make the point that attitudes in mining companies need to change – a not impossible task, and that much is already happening in terms of autonomous operations. Finally we sketch a vision of how mining can be undertaken with negligible footprint and environmental impact. Such mines will be kilometres deep and will embrace in-place leaching and underground electro- winning, only bringing the valuable commodity to the surface.
Keywords sustainability, mine of the future, in-place leaching, mining automation
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1 | THE NEED FOR SUSTAINABILITY There has long been recognized a need for more sustainable mining. Environmental concerns have always been present and even long ago, were of relevance to local communities. Today, with global communications being so advanced, environmental concerns are shared around the world. As well, the concerns around the depletion of resources have been instrumental in raising the awareness for a systematic approach to sustainability, one that includes environmental concerns, resource availability and of course the direct and indirect stakeholders and communities. Despite the high profile of sustainability as a part of any mining development, agreement on how sustainability can be measured is still far from satisfactory. As we all recognize, “what gets measured gets done”. 1 2 It is informative to consider the fundamental trends that are driving the minerals industry as without some understanding of these trends, the targets for improvements in sustainability are too diffuse. Further, we will restrict the discussion to the next 20 years or so as further out, the balance between what is possible and what will happen becomes too diffuse. It has more to do with politics and expectations than technology or how companies behave. 1.1 | The demand side By far the strongest force shaping the minerals industry is the demand side. World population is growing, estimated to be 8 billion by 2030 3. At the same time the population is urbanizing. The trend in Figure 1 is clear and likely is unstoppable. As this urbanizing population increases its GDP, demand for minerals and metals follows. No country in the world through all of history has escaped this increase in demand as the GDP/head increases. With the world standing at aprox $10,300 GDP per head in 2012, the projected figure for 2022 is $15,000 per head and for 2030 $18,000 per head. An ongoing and rapid rise in demand for almost all commodities is inevitable. So the pressure on sustainability is 00 1 great indeed.
1 Batterham 2003 2 Batterham 2013 3 United Nations World Population Prospects, 2011
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0% 1750 1800 1850 1900 1950 2000 2050 2100 Figure 1. The increasing urban population means increasing demand Source: United Nations, 2011. 1.2 | The Supply Side Since the time of Malthus, there have been predictions of shortages of minerals and other commodities. One of the most detailed was from “The Club of Rome” 4 who suggested in 1972 that we would run out of oil in 1992, of gas in 1994 and of coal in 2083. Clearly we have not run out and it is important to understand why. One can note however that the grades mined, when averaged globally have been falling as more and more is mined. This trend has been going on for many centuries. Indeed, using copper as an example, forward projections of grade are to fall from 1.1% now to around 0.9% by 2025. And as grades fall, so the energy required to separate valuable minerals rises. Again using copper as an example and the extensive work of Marsden 5 we see that for all currently known routes, as grades fall, energy requirements increase. Interestingly, in Australia in the last 30 years, the average grade mined has reduced by 50% and the average energy used has increased by 70% 6. This does not sound like sustainable mining.
4 Meadows, D.H., Meadows, D.L., Randers, J., & Behrens III, W.W., 1972 5 Marsden 2008 6 Energy Efficiency Exchange, 2013
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Figure 2. How energy requirements increase as grades fall. Source: Marsden, 2008. 1.3 | The Fundamental Trend That we have not run out of minerals even though demand has increased dramatically, grades are falling and the energy for mining and processing is increasing is easily explained by the march of technology. We continue to move down the resource pyramid because of the innovations that are made, both step change and incremental. In copper mining alone we have seen step changes in the last 100 years that have dramatically reduced costs and allowed more sustainable operations: • Flotation • Open pit mining • Heap-leaching • SX-EW • SAG mill circuits • GPS truck location We can conclude that there is no scarcity of energy and mineral resources. They are in reality ever more available at lower costs (in real terms) because of the innovations seen in the industry. In passing, this is not to say that market manipulation can in the short term (to 5 years) cause shortages and price spirals. Rare earths are a key example but there are others. The European 00 3 Union has listed 41 minerals and metals where it has concerns around market manipulation, with 13 of these being seen as strategically threatened. 7 In all cases however, the total supply
7 European Commission, 2010
4 BATTERHAM available and that needed for the next 30 years are seen as in reasonable balance. 2 | THE CHANGING FACE OF SUSTAINABILITY Previously, sustainability was relatively simple. Companies ensured they had a solid system of governance in the way they conducted business and paid attention to: • People o Especially social responsibility • Planet o Sound environmental management o Measured and reported environmental performance • Prosperity o Adequate economic returns to shareholders o Fiscal contributions to governments and other stakeholders The production side of the equation worldwide tends to be a good news story. As an example, in the phosphate industry 8: • More of the phosphate rock is mined • There are serious efforts on energy, water and dust reduction • Upgrading via washing, screening, cyclones, flotation is routine o In terms of salt water flotation the industry is well advanced • Despite increased demand, the amount of rock shipped is reduced due to vertical integration and better recoveries • Fertiliser usage is also improving o Demand per hectare is reducing o Less run-off to waterways But against these solid improvements, the environment side keeps becoming more complex. There are commonly demands not just on emission levels of noise, dust, gaseous and liquid emissions as there have been for many years but also a requirement to focus on: • Energy efficiency • Green energy sources • Life cycle of products • Waste management • Ecology and land use changes • Loss of biodiversity
8 Batterham, 2013
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• Depletion of resources • Environmental impact • Need to use less water And the public licence to operate is becoming ever more challenging to obtain and maintain. As a small example of the lack of logic that can prevail, the power industry in Germany, faced with bringing on more coal fired power to make up for the phasing out of nuclear power, has agreed that no cooling towers will be built as they are seen by the public as unsightly and polluting , with water vapour in reality. Governments are becoming increasingly aware of their power to participate in private mining projects as a sovereign right. Equally, citizens are demanding more involvement, more action targeting long term recoveries and attention to social concerns. Of the 223 registered socio-environmental conflicts recoreded in Peru this year from January through July, 72.3% were against mining operations.9 Sustainability now takes much more effort and time. All possible stakeholders must be identified and their narratives understood. Potential future scenarios have to be evaluated in order to develop engagement approaches for each constituency. The recent agreement by Rio Tinto in the Pilbara region of Australia has been heralded as a classic example of the new style for sustainability. The agreement delivered access to 70,000 square kilometres for exploration and development with the traditional owners receiving employment opportunities and compensation, eg every school leaver is offered a job. The process involves outlays of $2bn and took 7 years to bring to agreement. It started with considerable baseline community assessment and engagement to give key demographic, social and economic data. From there it moved to partnerships with the communities, NGO’s and governments. A long but successful journey. Understanding the stakeholders is the key that now has the highest priority in obtaining the public license to operate. Reggio and Lane 10 have comprehensively mapped out the diversity of 00 5 stakeholders and shown how it is inevitable that there will be conflicts of interests that must be balanced.
9 Business News Americas, 2013 10 Reggio & Lane, 2012
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Figure 3. Understanding the stakeholders. Source: Reggio R. & Lane A. 2012. One can conclude this section noting that sustainability itself has become far more complex in recent years, particularly in terms of obtaining the public license to operate. At the same time, innovation becomes ever more important as it is in the final analysis, the only tool available to generate more cash flow with which to better satisfy the needs of the stakeholders, despite lower grades and more energy needed for mining and processing. 3 | OPPORTUNITIES TO IMPROVE 3.1 | A Matter of Attitudes It has been argued so far that innovation is necessary to enable a better approach to sustainability. The challenge here is that innovation of necessity involves taking risks and companies are increasingly becoming more risk averse. This behavior is quite predictable when one considers the ever increasing pressure from shareholders, especially funds managers, for ever increasing returns. Companies respond by minimizing risk and maximizing production. Yet at the same time we need innovation and the lesson of history is that it will happen. Hollitt has succinctly summed up the conditions under which innovation is most likely to happen 11 . A new technology must have: • Some criticality for a new resource or a major expansion. This generally is because of the nature of the resource eg low
11 Hollitt M, 2012
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grade, unusual contaminants, excessive energy demand, environmental concerns, etc., • A clear business value and good NPV, • Better NPV than conventional technology, • Strategic significance, ie it positions the company with a long term, low cost resource, • And the company must have sufficient cash flow and resources available for more than one business cycle, reflecting the long time span for technology development and commercial implementation. This all requires leadership from the top. The point about middle managers that are under pressure to produce tonnes and to minimize risk is that they will tend to appoint new people who have similar attitudes and they will certainly be looking for people similar to themselves when it comes to promotions. The realities are that middle managers clone themselves and this is most likely to be inimical to innovation. Without leadership from the top, not much changes. Codelco recently announced their intention to harness the world’s largest solar plant for mining. Andres Alonso, Codelco’s Energy and water senior manager noted 12 : “internal resistance within companies is the biggest challenge for implementing projects such as Pampa Evlvira Solar. The mining industry finds it hard to be innovative because we produce 24 hours a day, seven days a week; if you say ‘let’s have a new way of operating, let’s change this issue’, this tends to be resisted as people want to keep on producing. It requires a great commitment from management. Fortunately there was great support from our management and we were able to overcome internal barriers that all mining companies have.” The conclusion is clear. If one wants to see more sustainability, there must be commitment from senior management not just for sustainability but also for innovation.
3.2 | Selected Topics for Innovation
It is beyond the scope of this paper to systematically review the 00 7 possibilities for innovation in mining and mineral processing. Opportunities abound in individual steps and in the overall process. A few examples will be given of each.
12 Mining News Premium, 2013
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The separation of valuable minerals from gangue at coarser sizes is the target for many developments. Clearly removing gangue at earlier stages of a circuit is beneficial and while potentially requiring more capital investment, can show very dramatic returns 13 . The question of course is how one does the sorting at coarse sizes. At lower tonnages, mechanical sorters have been most successful. Their range of minerals detectable and tonnages continues to impress. While 400 t/hour is quite an improvement on past performance, it is still a long way short of the thousands of tonnes per hour seen in hard rock mining. There are however alternatives, such as dry sand fluidized beds. Particles up to 30mm can be separated based on density, with particles heavier than the dry sand fluidized bed density sinking and lighter particles floating. The technique has been demonstrated for coal 14 , iron ore 15 and copper ores 16 . New methods of separation that are energy efficient are clear targets, especially when they allow separation at coarser sizes, thereby allowing grinding energy to be reduced. A further development here by Jameson 17 suggests that instead of a top size for flotation of around 200 micron, galena could be floated up to 1300 micron by using a more gentle form of flotation, viz. a fluidized bed. Comminution however still stands as one of the biggest challenges. It has been reported as responsible for 5% of the world’s total energy consumption 18 . When one considers the energy needed to create the fresh surface associated with size reduction to the actual energy expended in a comminution machine (such as SAG mills, ball mills and HPGR), remarkably, the process is only of order 1-2% efficient. This is a massive waste of energy and a clear target for improvement. That comminution should only be 1% efficient is explainable 19 : • The impact of particles on particles and balls on particles is random and highly variable
13 Pokrajcic, Z., O’Halloran, R., and Jones, C., 2010 14 Firdaus, M., O'Shea, J-P., Oshitani, J., Franks, G.V. 2012 15 Oshitani, J., Kawahito, T., Yoshida, M., Gotoh, K., Franks, G.V. 2011 16 Franks, G.V., Firdaus, M., Oshitani, J. 2013 17 Jameson 2010 18 Batterham 2011 19 Tromans 2008
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• In any individual collision, the loading force may be too small to propagate cracks • The loading force may be in the wrong direction for crack propagation High pressure grinding rolls should overcome some of these factors but in practice give only a marginal improvement in energy consumed. Recent work on comminution at the University of Melbourne and similar work on the micromechanics of particle interactions by the CSIRO has suggested that particles build chains that carry much of the applied loads. When these chains are disrupted, eg. by one particle in the chain breaking, the remaining particles shed their strain energy as heat and sound. This explanation is suggestive of why the comminution process is so inefficient. It also suggests that a step forward would be to combine compression (for breakage) and shear (to disrupt the force chains). Major innovations are necessary to facilitate a greater degree of sustainability. Perhaps in the future we will see more of the innovations being undertaken by equipment providers rather than by the major mining companies. This would be following what has already happened in the oil and gas industry where one of the suppliers (Schlumberger) now has a market capitalization greater than many of the companies it supplies equipment to. Schlumberger appear to have obtained this position by championing innovation – a message for the mining companies. 3.3 | The Mine of the Future – Happening Now Automation has always been a key target for innovation in mining and mineral processing. Several definitions are possible and here we are referring to operations of individual units without human intervention or with the human intervention being remote from the operation. Drills, trucks, drag lines, trains, loaders and mineral processing plants are now operated without human operators. What is new however and is a game changer for innovation is the concept of mining being “data mining” whereby the original information on the ore is carried through the operations so that 00 9 final blending does not require stock piles other than whatever transport, such as a ship, is used to take the product to a customer. This is one part of the Rio Tinto “Mine of the Future™”. Components of this approach include the first long-distance heavy haul system of its kind in the world (over 1500 km rail network), autonomous drills with the first cab-less drill already in operation,
10 BATTERHAM over 3 years experience with autonomous trucks with over 150 trucks scheduled to be in service by 2015, remote operations centre for 31 pits in 14 mines and 3 ports, and in the near future, remote “excellence centres” providing 24/7 support for operations globally. The cost of this brave adventure by Rio Tinto is many $100’s millions.20 An automated mine is laid out differently to a conventional mine. It is laid out in a pattern that enables the smooth flow of its robot machines, more like a railway than a road system with all of its intersections. Since the first implementation steps in 2008, Rio Tinto has already seen significant benefits, eg 50% reduction in schedule variability, 30% increase in train dumper productivity, no safety incidents in 900 days of autonomous vehicle operations and much higher consistency in drill operations. Clearly, this path to the “mine of the future” is already happening and will facilitate more and sustained efforts in sustainability. 3.4 | The Mine of the Future – Still to Come Many have dreamed of the ultimate, sustainable mine of the future. What might such a mine look like: • Only the valuable component should reach the surface o This implies some form of in-place processing • The mine should have negligible surface footprint o Most likely therefore underground o And deep to prevent any subsidence • There should be no interference with aquifers of surface waters o This suggests very deep mines, below any aquifers • Energy and water requirements should be minimal o This implies quite different methods of liberation Using copper as an example, the discovery of very deep (1-2km) copper mineralisations at reasonable grade is a good starting point, eg Resolution Copper in Arizona with an inferred resource of 1.5bn tonnes at 1.47% copper 21 . While this mine is likely to be a conventional block cave, it is easy to see how such a deposit could become a true “mine of the future”.
20 McGAGH, 2012 21 RESOLUTION COPPER, 2012
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Figure 4. The mine of the future: deep, fractured by caving, in place leaching using advanced biohydrometallurgy and the copper won electrochemically underground. Source: Batterham, 2003. What do we need to make such a mine happen? The answer is surprisingly little, especially when compared with the effort going in to the here and now “mi ne of the future” via automation. Let us look at the steps of this much more sustainable mine in turn: • Exploration should preferably be near large cities where skilled graduates are available and prepared to work. As the footprint is negligible, being near a large city should be acceptable. • Deep exploration has not been on the agenda to date but is quite possible, especially using gravity gradiometry. • Providing access to the mineralization for equipment and later, for processing must be far cheaper and safe r than current shaft sinking methods. Shaft sinking rates and methods have not altered much in the last 50 years. The breakthrough here will be fully mechanized shaft sinking, as envisaged some years ago by the Robbins Company and more recently by Herrenknecht. • In the first step for recovery, the mineralization must be opened up to allow in-place leaching. The most obvious way of doing this is to cave some material from under the mineralization and bring this material to the surface. The demand for clean ro ck for construction in any large city is significant. Similarly, tunnel access for the caving operation 00 11 and later to provide underground processing facilities can be envisaged using fully mechanized and autonomous machines. Such machinery is available now.
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• The key step of in place leaching deserves special mention. We can assume that the mineralization is well below any aquifers of commercial interest. The question is then how might chalcopyrite be leached into solution economically. The answer is that biohydrometallurgical processes have already been demonstrated in the laboratory and their application first on heaps at surface and then deep underground is only a matter of time. • Somewhat surprisingly we can conclude that the “mine of the future” is quite feasible and would, when realized, offer the world a far more sustainable version of mining.
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