CHAPTER 1.3                                  Future Trends in Mining                                            Tom Albane...
22	                                                              SME Mining Engineering Handbook                          ...
Future Trends in Mining                                                     23approach on energy. The opportunities and th...
24	                                                SME Mining Engineering HandbookImproved Early Decision Making          ...
Future Trends in Mining                                                  25excavators must be exceptionally reliable to im...
26	                                              SME Mining Engineering Handbookthis opportunity must be followed up. The ...
Future Trends in Mining                                                  27     Automation will require the transfer and m...
28	                                                SME Mining Engineering Handbookat the mine site or mine output is doubl...
Future Trends in Mining                                                    29     The importance of construction quality c...
30	                                                SME Mining Engineering Handbook2019 provide an interesting insight into...
Future Trends in Mining                                                  31                                               ...
32	                                                     SME Mining Engineering Handbook                                   ...
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  1. 1. CHAPTER 1.3 Future Trends in Mining Tom Albanese and John McGaghINTRODUCTION and stadiums, and they gain the wealth to purchase consumerImagine for a moment the mine of the future, where knowl- goods, such as refrigerators, cars, and air conditioners. Withedge of the ore body, its mineralogy, size, and value are known urbanization comes a greater demand for metal. It is estimatedprecisely, based on a range of three-dimensional (3-D) geolog- that the average per-capita requirement for metal products isical images captured nonintrusively long before mining com- 155 kg for China’s rural communities and 817 kg for China’smenced. The mine plan covers not only the initial target ore urban dwellers.body but all future extensions until the reserve is exhausted. Demand for all base metals, particularly iron, copper, andNothing is left to chance. Imagine a mine with a zero envi- aluminum, will likely double from 2010 to 2025, due largelyronmental footprint and zero net energy consumption, where to this population shift. Putting this in perspective, the addi-all processes are continuous, with process control systems tional demand for iron ore in that time period is equal to thethat monitor and optimize performance, and where all mov- capacity of five Rio Tinto Pilbara operations, which produceing equipment is autonomous and controlled from afar. Few close to 200 Mt per year. It is also estimated that the world willpeople are visible on or under the ground, and the work envi- consume as much copper from 2010 to 2035 as it has duringronment is safe and healthy. Highly skilled workers operate the last century.the mine from air-conditioned control rooms in major capital China’s iron ore imports are expected to double fromcities. These jobs are well paid and highly prized. 2010 to 2016 (Figure 1.3-1), following many years of growth Can we imagine this future, and is it that far away? The that has made China the world’s largest consumer of tradedpace of change in the industry has increased dramatically, iron ore, copper, and aluminum (Table  1.3-1), together withwith strong market pull and strong technology push. The mine nickel, steel, and coal. From 1990 to 2006, China’s steel pro-of the future may be closer than we think, and many of the duction more than tripled, with iron ore imports increasingenabling technologies exist today. The trends likely to shape 20-fold during this period. China is clearly the new force inour future will be explored through this chapter. commodity demand. The industrialization of China and India is changing the economic world order.DemandAlthough the pace of change continues unabated, the nature, Supplyrate, magnitude, and impact of change are not constant and Satisfying this huge growth in demand is the mining indus-know no boundaries. No one predicted the coming of the infor- try’s greatest challenge, and one that must be confronted headmation age and the enormous global impact of the Internet. on. The industry must think and work differently to keep paceThe mining industry is changing in step with global demands, with this burgeoning demand. The old ways will not be goodbut the challenges of supplying minerals and metals to a world or fast enough. Change is essential.experiencing exponential change are great. The future will be Mine output rates must increase. Existing assets must bevery different. extended to yield more. Lower-grade reserves must be tapped. The mining industry is experiencing a dramatic change, Exploration and discovery must become more efficient. Theone that profoundly affects our industry, an unprecedented search for new high-value reserves must accelerate. These out-change that creates an enormous challenge and an immeasur- comes must be delivered during a global industry skills short-able opportunity. The world is rapidly becoming urbanized, age and against a background of diminishing surface depositswith an additional 1.4 billion people predicted to move into and rising costs. Moreover, in today’s society, everyone wantscities within 20 years. Although the population shift will be more for less. Higher outputs must be achieved at lower unituniversal, it is being led by China and India. People who costs. Working against this need for lower costs are increasingmove to cities require houses, roads, schools, power stations, energy costs, the threat of climate change, and the higher cost Tom Albanese, Chief Executive Officer, Rio Tinto Ltd., London, UK John McGagh, Head of Innovation, Rio Tinto Ltd., Brisbane, Queensland, Australia 21
  2. 2. 22 SME Mining Engineering Handbook 1,500 Actual Forecast 1,200 Rest of World Million Metric Tons 900 600 China 300 0 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 Source: Albanese 2008. Figure 1.3-1  Seaborne iron ore importsof mining deeper ore bodies and lower ore grades, possibly in Table 1.3-1  Growth in China’s share of global consumptionmore challenging geopolitical environments. of metals (%) Efficiencies must be found in all operational areas, from 2001 2002 2003 2004 2005 2006 2007E* 2011Eexploration to extraction. The solution to efficiency improve-ment lies in the development and implementation of new and Aluminuminnovative technologies. Companies that innovate are more China 15 16 19 20 22 25 31 41likely to be rewarded with lower costs, improved competitive USA 22 22 21 20 20 18 15 12positions, superior returns to shareholders, and sustainable Copperbusinesses. And the mining industry must deliver these outcomes in China 16 18 20 20 22 23 24 26an environmentally sustainable way. The planet is warming USA 18 16 15 14 14 12 11 11because of human activity. Atmospheric levels of greenhouse Iron Oregases are increasing. The mining industry is not insulated China 30 32 34 39 46 51 53 54from the effects of global warming, and we must play our partin dealing with it. As miners, we must take sustained action to USA  5  5  5  4  4  3  3  3reduce the environmental impact of our operations. We have Source: Albanese choice. If we do not reduce the size of our footprint, those *E = estimate.who are in a position to give us a license to operate will nolonger do so. Our aim must be to achieve both zero emissionsand zero net energy consumption. A suite of technologies that our house be in order, but we must ensure, through better com-could support such a vision is under development. munication, that the wider community knows it is. All of this must be achieved in a world where stakeholder Finally, while innovation may hold the key, today’s newconsultation is assumed and affected communities benefit technology could well be next year’s standard practice, sofrom mining activities through and beyond the life of a mine. innovation must be a continuous process through the eco-Consultation with local communities and other stakeholders nomic highs and lows. A cultural change is needed. The goalmust continue to evolve through all stages of a project, includ- is an environment in which workers constantly seek newing the ultimate mine closure. This necessity increases as the and better ways of doing things and in which innovation issearch for new tier 1 reserves takes exploration to less acces- rewarded. New ideas must be continually developed and nur-sible and more sensitive remote areas, often in Third World tured. The same systems and cultural changes that brought thecountries. world higher quality, better customer service, and improved The mining industry works under intense scrutiny, and safety can drive innovation in the mining industry.rightfully so. We live in the information age. People are more The challenges are universal and demanding—theinformed, and information is available to many people at the increasing demand for commodities; grades and their declinetouch of a button. They are aware of the environmental chal- with time; mineralogy and the need to handle more complexlenges confronting this and future generations. They are more ores; the need to find new reserves; disposal and minimizinglikely to act on what they see and take action against those of wastes; and the availability of water, power, and skilledwho do not accept that the risks to our future are real and labor. These challenges are combined with increasing expec-against those who act irresponsibly. We must deal with the tations from the community and concerns about sustainabil-intense scrutiny that comes with this new age. Not only must ity and safety and climate change, forcing a more targeted
  3. 3. Future Trends in Mining 23approach on energy. The opportunities and the rewards are Company reputation will influence the outcome, and finan-great. Those mining companies that meet the challenges will cial considerations are also critical. Different skill sets will bebe in a stronger competitive position. A vision for the future is required. After government approval is given, exploration inprovided in the following sections. remote, unstable, or environmentally sensitive regions must be efficient, and less-intrusive methods for detecting mineralsEXPLORATION AND GEOLOGY must be employed.Logic would suggest that it is easy to find things that havealready been found. In the mining world, it is hard to argue the Geologypoint when just about every square kilometer of the developed In addition to target identification, geology has to better pre-world has been surveyed to some extent. It follows that if we dict how ores are expected to behave during the stages ofare to keep pace with demand, exploration and discovery must mining and metals extraction. To optimize cash flow, suchbecome more efficient and the technology used to detect and ore knowledge is applied throughout the value chain. In thecharacterize mineral deposits on and below the earth’s surface medium to long term, ore characterization methodologies willmust become more capable. Vast amounts of money are being be improved through better measurement techniques, predic-spent on exploration. In 2002, global exploration expenditure tive capability, and early decision making.was in the region of US$2.5 billion, and by 2007, it had risento more than US$10 billion. The identification of the geologi- Improved Measurement Techniquescally rare tier 1 deposits is the highest prize. Such deposits New technology allows for higher-quality results that can begrow with exploration, commonly have other tier 1 deposits provided in a shorter time frame, hence increasing resolution.nearby, and support production expansions. Their discovery Such improved characterization will allow for better defini-is a necessary part of the total solution to satisfying growing tion of the reserve, which impacts the economic value of theglobal demand for minerals and metals. deposit. Increased ore-body knowledge and associated technicalExploration developments allow more complex ore bodies to be potentiallyThe aim of exploration geology is to find mineralized target exploited. And better characterization of the resource is usedareas for development into profitable mines. To define an eco- strategically; that is, which ore bodies need to be progressednomic deposit involves a number of steps—from initial small- through the prefeasibility, feasibility, or order-of-magnitudescale sampling to larger-scale characterization. History has stages.repeatedly shown that the probability of converting explora- In normal circumstances, confidence in data collectedtion targets into economic deposits is low. In the future, there- during project development from exploration to feasibilityfore, the key challenge for exploration geology is to increase study increases as the project progresses. Some of the mea-this probability of success by identification of surement and testing technologies that are likely to be further developed in the future include automated core logging, core • A wider range of deposit types, including lower-grade imaging, and on-line and near-online analyzers. ores, deposits with different mineralization styles, and ores with greater variability, possibly in areas already Improved Predictive Capability explored; Improvements in 3-D modeling capability will increase the • Deposits that do not occur at the surface or are covered ability to predict both mining and processing behavior from and possibly in areas already explored, near existing ore measured primary data. Key elements that need to be known bodies, or even below existing mine sites; for base and precious metal mining operations include blast- • Targets that are potentially more remote; ing, crushing, grinding, liberation, and recovery characteris- • Deposits in more politically sensitive or unstable regions; tics. Other related issues include tracking deleterious elements and and minerals, providing inputs into the environmental man- • Deposits in more environmentally sensitive regions. agement of waste rock, and increasing the energy efficiencyThe discovery of ore bodies or mineral resources in any of of processing equipment:these categories will present financial, political, and scientific • Improved prediction of ore-body behavior in mining.challenges. More knowledge at the early stages of projects improves Interestingly, Davy analyzed all kimberlites/lamproites decision making on mining methods; for example, fordiscovered from 1966 to 2003 (excluding those in Siberia and the prediction of fragmentation, crushing, and grindingRussia) and observed the following (Davy 2003): and for the optimization of blending strategies. In under- • The frequency of discovery doubled through the 1990s ground mining, improved cave models can be used to compared with the 1980s as more money was spent on optimize draw strategy. exploration and more junior diamond explorers were • Improved prediction of processing behavior. active. Metallurgical data in the block model improve decisions • More world-class projects were discovered in the 1990s, about processing methods and allow for the prediction of lending support for the view that, with improved methods performance for specific ore types and ore blends. The and new technology, world-class deposits are still there data are also used for concentrator optimization and met- to be found. allurgical accounting. • Improved prediction of behavior into the environment. Before discovery, however, the rights to explore a pro- It may be possible to minimize the environmental impactspective area of land must first be acquired, and this is not of mining and predict environmental impact and cost bywithout difficulty, especially in a competitive market. incorporating environmental data in the block model.
  4. 4. 24 SME Mining Engineering HandbookImproved Early Decision Making environmental sensitivities that preclude blasting or adverseHigher data density (but lower cost) and increased predictive pit floor conditions could support mechanical cutting and con-capability will enable the industry to more confidently reject tinuous material movement.exploration targets that are deemed uneconomic. Explorationprovides a significant return on investment. Despite that, the Blasthole Drillingcost is high and future tier 1 assets will be harder to find, so Blasthole drilling offers the opportunity to gather more infor-technological advancements and process improvements that mation on the strata and rock encountered during drilling.shorten the discovery cycle and increase the probability of Today, the data associated with drilling—torque and pull-success need to be developed and implemented. down force—are either not logged or are used in a fairly basic manner. In some instances, rock, or strata, recognitionSURFACE MINING is performed by correlation of drilling parameters with rockThe advent of surface mining stands, arguably, as the most hardness, but the technology’s acceptance is not widespreadsignificant change to the fundamentals of the mining process. despite numerous positive applications and case studies. TheThe move to open-pit mining, which started in the 1890s with most often cited reason for the lack of acceptance is the needadvancing mechanization, has dramatically simplified the pro- to retrain the algorithms at the heart of the system as the drillcess of extracting minerals. A rich history of innovation has moves into different domains.brought surface mining to where it is today, with mine out- In the future, real-time feedback from the drilling rigput rates that were unimaginable even a few decades ago. But will be regarded as routine. In addition to the drill param-what does the future hold? Surface mining is subject to a wide eters and rock recognition, sensors in the drill will performrange of internal and external pressures, so change is essential a variety of duties ranging from elemental ore analysis toto meet the challenges ahead. It is no longer just about moving the measurement of geotechnical rock mass much rock as safely and cheaply as possible. Recently, auto- Discrimination using a variety of measured and derived prop-mation and remote control of mine processes have taken center erties will move the industry toward greatly improved diggingstage, and this is likely to continue into the foreseeable future to ore–waste boundaries. Advanced blast design packages willas advances in communication systems, measurement systems, become more accepted and more sophisticated, with the pack-and computational power provide unlimited scope for develop- ages linked directly to the charge loading trucks. The linkagement. As well as these technologies, there are still many areas will be wireless and will replace the manual exchange of data,where both step-change and incremental improvement can add thus leading to the planned loading of a range of explosivetremendous value to the surface mining sector, and the industry types and densities. The correct delivery of optimized blastappears to be poised to pursue these opportunities. designs will ensure greater predictability in fragmentation and muckpile shape, which in turn will lead to improved diggingFragmentation conditions and reduced operating costs.Fragmentation in hard-rock surface mines is almost entirely The advanced drill-blast-load loop is heavily dependentdependent on explosive rock breakage, and this is unlikely to on the deployment of a variety of sensors. Every time wechange in the foreseeable future. In terms of effectiveness and touch a material, we must learn something about it. The usecost, blasting provides the ability to liberate large quantities of of sensors and their integration into standard operating proce-material to a size that can be moved using standard excavation dures will enable miners to increase operational effectivenessand transport equipment. even when there is a skills shortage. Given that blasting lies at the core of the mining processchain, it is not surprising that considerable research has gone Materials Movementinto explosive formulation, initiation techniques, and simu- A major challenge lies in how best to get material out of alation. The Hybrid Stress Blast Modeling research project is mine. In early open-pit mines, locomotives moved much ofan example of current research that is exploiting the increase the material in the larger pits such as Bingham Canyon, Utahin computing power to apply sophisticated numerical model- (United States). The move to trucks was a major step forwarding codes to the process of blasting (Batterham and Bearman in flexibility and has driven the increase in open-pit mining.2005). The knowledge of fragmentation and muckpile forma- In open-pit mining, equipment size matters and equates totion that can be yielded by this approach will enable blasting productivity: more material moved in a given time. For thisto be better matched to downstream requirements. This is part reason, the trend will be for ever larger equipment. Althoughof the move toward an optimized mining process, free of dis- the trend has been focused on the size of haul trucks, to loadruptions from poor blast performance. these larger vehicles the size of loading equipment has also Alternatives to explosive fragmentation in surface min- increased commensurately. Currently, haul trucks with pay-ing are limited by the amenability of the ore body, in terms of load capacities of up to 365 t (metric tons) carry loads fromboth material properties and geological structure. The barrier the mine face to the tip point, a 12-fold size increase in pay-to widespread use of mechanical excavation is the difficulty of load capacity since 1950. To satisfy the enormous appetitescutting hard rock and the high cost of machine wear and tear. In of these trucks, excavators with buckets of up to 45 m3 andmines where material is amenable to mechanical cutting, sig- payloads of more than 100 t are in use, enabling even the larg-nificant proportions of production are being delivered without est haul trucks to be loaded with four passes, thereby ensuringblasting. In these instances the driver tends to be selectivity, a quick turnaround.linked to the fact that the ore thickness is significantly thinner But what is the ideal size of a haul truck: larger, smaller, orthan the normal blast-sized smallest mining unit. Therefore, the current size? The answer is uncertain, but the trend towardif mined using traditional open-pit bench heights, the degree larger vehicles shows no sign of slowing. Fewer, larger trucksof dilution would be excessive. If selectivity is not a prime reduce flexibility, increase risk, reduce mining selectivity, anddriver, then factors such as reduction of diesel consumption or drive up the size of ancillary equipment. Larger trucks and
  5. 5. Future Trends in Mining 25excavators must be exceptionally reliable to improve avail- of considerable research into alternative fuels, including theability and ensure that productivity targets are met. Smaller development of a hybrid diesel-electric locomotive that nottrucks drive up cost because of number, maintenance, and only reduces emissions but reduces fuel consumption by cap-larger work force. The trend in size will be strongly influ- turing and storing energy dissipated during braking. It prom-enced by what best suits an automated mine operation, where ises both cost and environmental benefits. The efficiency ofreduced cycle times and increased availability will deliver the overall rail network is also a major consideration, and, inproductivity gains. Limitations to further size increases may addition to the application of advanced optimization models,also come from engineering and material constraints. there is a move to autonomous train operation. Trucks, predominantly diesel-electric, provide flexibil-ity and can move anywhere. Despite increases in efficiency, Planning and Schedulingthe diesel use is significant, and its reduction is a major chal- As the mining industry moves toward more complete inte-lenge to the industry. Alternative energy sources for trucks gration of production systems, planning and scheduling willmust be developed. Driven by the need to reduce greenhouse change dramatically. Whereas plans and schedules for mining,gas (GHG) emissions and reduce dependence on petroleum maintenance, and logistics were once developed in relativefeedstocks, the global automotive industry is moving rapidly isolation, the trend is toward whole-of-business planning andto develop alternatives to the embedded internal combustion scheduling. Distinctions between long- (strategic), medium-engine. Hybrids may be part of the solution. Hydrogen fuel and short-term planning may remain, if only for convenience,cells offer some promise, and biodiesel based on waste bio- but business processes and software systems will evolve suchmass may be a viable alternative fuel for internal combustion that plans and schedules developed with different time hori-engines. Certainly, the automotive industry’s experience will zons will influence and be influenced by others:flow onto the mining industry, and early adoption of a viable • Plans and schedules will become adaptive, responding toalternative can be expected. increased granularity in space and time information. Electrically augmented trucks fed from an electric pan- • Real-time sensing of material geometallurgical propertiestograph (overhead power lines) are deployed at some sites, will influence the mining sequence and downstream pro-with their original installation driven by the fuel crisis of the cessing in close to real time.1970s. Their reduced flexibility and difficulty in changing the • Short-term production schedules may even respond tosize of trucks due to the fixed overhead infrastructure limits short-term fluctuations in market needs.their widespread application. Given the current fuel situation,development in the field could be expected. Although the next step-changes in mining methodologies Alternatives to haul trucks must be considered, particularly may not be immediately apparent, every change introducesin view of ever-increasing energy costs. The obvious alterna- new challenges for planners and schedulers. Software systemstive is a conveyor system for flat areas or high-angle conveyor for mine planning and scheduling will evolve to cater to thesesystems to reduce diesel-intensive uphill hauls, but there are and other mining options.drawbacks. A conveyor is more fixed and can transport well- Formal optimization algorithms have long been used tofragmented material but cannot take run-of-mine blasted mate- design optimal pit shells, aiming to maximize project net pres-rial, unlike haul trucks. For conveyors to be effective, the top ent value. But optimization is likely to be applied much moresize of material must be controlled and this can only be guaran- systematically throughout the production process, not onlyteed currently by size reduction through crushing or mechanical from mine to mill but from pit to port. Decisions that reliedcutting. In-pit crushing is a solution to this dilemma, which has on experience in the past may one day be supported by almostbeen deployed at various sites over the years, but the challenge continuous re-optimization of the production process. Genetichas always been such units’ mobility. Recent developments in and evolutionary algorithms will complement parallel effortsmobile crushers and the use of conveyors have created greater to solve large mixed-integer linear programming techniques.opportunities with future developments in this field expected to Optimization algorithms will account for uncertainty in allwiden the application of the technology. Further, mechanical parts of the production process, from variability in geometal-excavation could provide the consistent material flow suitable lurgical properties to reliability and availability of fixed andfor a conveying system in amenable materials. mobile plant to fluctuations and trends in costs and commod- Long-haul, or out-of-mine transport, presents a further ity prices.set of challenges in the future. Long-range overland or aerial As the mining industry moves toward automation andconveyors offer some alternatives. Many significant overland autonomy, the movements of individual vehicles will beconveyors have been deployed to great effect, and recent planned and scheduled at ever-decreasing time scales. Somedevelopments in aerial conveying systems could provide fur- vehicles will effectively control themselves. Short-term minether alternatives where terrain is unfriendly to the overland plans may define the broad parameters, but conventional dis-version or where the system must traverse environmentally patch systems may become a thing of the past.sensitive areas. From an energy perspective, conveyors of For the foreseeable future, explosive rock breakage andboth types offer the option to use regenerative technology to the use of haul trucks and excavators will remain an integralfeed power back into the energy system. part of hard-rock surface mining. Dramatic increases in the Pumping has not traditionally been considered as a mate- use of automation and remote control of mining equipmentrial movement system, but with improved knowledge of will shape the future of surface mining. Underlying all futurerheological flow properties, there are moves to examine the developments will be the ability to significantly increase thepumping of slurries containing much larger particles. sensing, measurement, and monitoring of critical geological, The traditional transport option for long distance, includ- geometric, and equipment-related parameters. Every time aning mine to port, is rail. Locomotives are currently the focus opportunity arises to gain knowledge by taking a measurement,
  6. 6. 26 SME Mining Engineering Handbookthis opportunity must be followed up. The effective integra- developments, most mining companies will not want to incurtion and use of these data will provide the backbone of future the high costs and will prefer to buy technology from special-advances in surface mining and will enhance the ability to ist suppliers. Mining companies will need to develop a methoddeploy the automated systems that are such a critical part of for overcoming this nexus because the provision of a completethe future. turnkey automation package by a single supplier is unlikely to happen in a timely manner.AUTOMATION AND REMOTE OPERATION Underground mining, where the imperatives for change areThe automation of mining processes is a technological step- much greater, was the first bastion to fall to equipment automa-change that will provide part of the solution to the indus- tion. Space is tight, the dangers are greater than surface mining,try’s most pressing challenge: achieving higher outputs to and health issues are of greater concern. Unmanned vehiclessatisfy the projected continuing growth in commodity metal are now more common. Vision and guidance systems enablerequirements. a remotely controlled vehicle to know precisely its location Automation also addresses the shorter-term imperative of in a mine by comparing the camera view with stored images.maintaining a suitably qualified work force at remote mine Vision systems improve the ability of a remotely controlledsites, which is an industry-wide problem. Younger generations vehicle to approach a rock pile and optimize the load collected.are reluctant to leave the comforts of urban life, where they The combination of these semi-smart machines with effectivesee their futures. Although work forces can be maintained in communications infrastructure enables tele-remote operation ofmining regions, the cost of doing so is extremely high, not underground machinery by operators sitting in safe and benignonly in direct wages, training costs, and penalties that have to office-like environments and allows machinery to be operatedbe paid to professionals and skilled workers alike, but also in in areas where the dangers preclude human operation.housing and other infrastructure needed to support the workforce. Vision for the Future The mine of the future might includeBenefits of Automation • A mine site where automated blasthole drill rigs perfectlyAutomation increases the level of control in what is inher- position every hole, conduct analysis during the drilling,ently a chaotic process by applying more stringent rules to and tell the explosives delivery vehicle what explosivesdecision-making processes and removing the randomness load and blend to be charged to each hole;inherent in isolated decision making. Applying a controlled • An excavator that can “see” the difference between oreprocess to variable mine geology and ever-changing topogra- and waste in the muckpile, can separate the two, andphy results in higher productivity and lower cost. Automation automatically load the driverless haul truck before dis-involves the collection and use of data; for example, gathering patching it;data from the blasthole drilling process, which enables hole • Driverless trains fitted with an array of sensors thatplacement and blast design to be better controlled and blast enable them to see beyond the horizon and that can traveloutcomes to be predictable and optimum. in a convoy as though linked by some invisible thread; Another benefit of automation comes from increasing the • A haul truck that automatically reports to the workshop asutilization and performance of haul trucks and other high-cost scheduled maintenance becomes due; andcapital items. With improved control comes a reduction in the • A haul truck with none of the design constraints that comeexpected levels of wear and tear and breakdowns, enabling with having a driver—no cabin, windows, air condition-preventive maintenance to be better planned and performed. ing, nor headlights; that is more symmetrical, possiblyMoreover, the amount of wear and tear will be reduced able to travel in two directions equally; and that comesbecause the autonomous machine is operated constantly with the current energy system and drive train—all-wheelwithin its design envelope. Costly breakdowns and unplanned drive and steering, electric motors driving each axle,maintenance should be avoided, as the cost of the repairs are power generators, and storage systems under body.higher than planned ones, but more importantly, the disruptionto the production process cascades through the system with If these and other systems were put together, it is easy to imag-costly knock-on effects. Attempts to control wear and tear ine the mine of the future operating similar to a rock factorythrough driver regulation have had limited success because where all functions work in unison, more like a productionsuch regulations are not easily enforceable. Higher availabil- mine than the variable mines seen today.ity and utilization means higher productivity and lower unitcosts. Another significant benefit is the large fuel savings that Automated Mine Sitecan be achieved by optimizing the vehicle operating param- In surface mining, “islands of automation” in haul trucks,eters, a vital consideration in times of high oil prices and con- blasthole drill rigs, shovels, surveying, and blasting arecern about GHG emissions. being developed. These independent developments must be Clearly, the time is right for automation, but it will not integrated, which will multiply the benefits that would oth-happen overnight. The technology for a fully autonomous erwise be achieved. Integration avoids unnecessary duplica-mine must be developed, but it is unlikely that any one single tion of enabling systems such as navigation and providescompany could take on the challenge alone. The disparate, operational standards and links all data sets. To avoid pos-independently developed pieces of the automation puzzle sible choking of the available bandwidth, developments inwill need to be connected and synchronized. This will require wireless communication are needed. Although individualthe industry to adopt automation standards that allow this pieces of equipment will need to become smarter to reduceto happen. Even so, the cost of automating all of the func- the communications requirement, a central “brain” to con-tions in mining will be a lengthy and costly endeavor. If duct the disparate mining activities must be developed andthere is no sustainable competitive advantage from in-house implemented.
  7. 7. Future Trends in Mining 27 Automation will require the transfer and manipulation of track that serves its Pilbara operations. The cost is high. Thishuge amounts of data. Autonomous operations, such as drill- will be the first time automation has been used in a heavy-ing, surveying, blasting, and loading, will each link to the haul railway of this scale, though the technology successfullybrain or autonomous backbone, which provides the coordi- operates on many metropolitan passenger railways around thenation and sharing of resources that will be essential to the world, where it is safe and reliable. Automated operations willautonomous mine. The know-how to develop this backbone integrate with the existing train management system and willwill likely be developed in-house by the mining companies in bring efficiency gains through greater scheduling flexibilityorder to tailor it to the mining process. Perhaps in the future, and the removal of delays. Additional safety systems are beingas technology advances, it will be supplied as a turnkey sys- developed to meet safety levels required for automated trains.tem from original equipment manufacturers (OEMs). Rio Tinto is working closely with the Western Australian A key capability of the backbone or brain will be the Office of Rail Safety to ensure that all safety requirementsability to effectively fuse the data from the disparate sources are met.around a mine. Data fusion differs from data warehousing.Whereas data warehousing requires the storage and use of Operations Centerdata to extract value, data fusion integrates data that offer a Rio Tinto has established an operations center in Perth,conflicting view of the world prior to the data being used. Data Australia, to manage operations in the Pilbara mines, aboutfusion is essential for a process that integrates and automates 1,300 km away. This is a key step on the path toward a fullyseveral functions. automated mine-to-port iron ore operation. At full opera- An example of the need for data fusion is to precisely tion, it will house hundreds of employees who will workknow the position of an autonomous moving vehicle in a mine. with Pilbara-based colleagues to oversee, operate, and opti-A Global Positioning System (GPS) provides a good indicator mize the use of key assets and processes, including all mines,of a vehicle’s position, but it is not fail-safe, so a backup is processing plants, the rail network, ports, and power plants.needed. Inertial navigation systems can provide information Operational planning and scheduling functions will also beon position as can wheel encoders that measure the distance a based in the operations center, where staff will also managevehicle has moved. A fast-moving vehicle such as a truck will power distribution and maintenance planning. Although thelikely have all three. To integrate these three sets of data and goal is a more efficient operation, an additional benefit ofapply uncertainty theory to determine the most likely posi- establishing an operations center within a capital city is thattion of the vehicle, data fusion is required using algorithms. it will directly confront the high cost of basing employees atAll of this data handling must be performed rapidly to ensure remote sites. This center is but one part, albeit a very impor-feedback to the vehicle and the autonomous brain controlling tant one, in a fully automated operation that includes driver-the array of resources in the mine. This is but one example less trains, autonomous trucks, and autonomous drills.of data fusion requirements in an autonomous system, and it In mining, the traditional coal face is where many ofheralds the future types of employees that mining companies the worst accidents happen and occupational illnesses arewill need to design and run information processes. sown (Cribb 2008). An inestimable benefit of automation The experience from the development of an autonomous and remote operations is the improvement in human health,mine will impact future mine planning. For example, the pre- safety, and well-being as a result of moving people out of thecise control of haul truck movement may create an opportu- danger zone. So although the absolute number of jobs mightnity to build narrower and longer haul roads. not change with automation, the overall safety performance of the company will improve as a direct result of workerTechnology Development displacement.As discussed, the vision of a fully automated remotely con-trolled mine is deliverable but will take many years, substan- Computing Powertial investment in research and development, and a broad The mining industry has experienced significant growth incollaborative network involving OEMs and leaders in auto- the utilization of computers since the mid-1980s due to wide-mation. The creation of a fully automated mine could not be spread adoption of personal computers. For iron, aluminum,achieved by even the world’s largest miner working in iso- and copper mining, it is expected that the computing powerlation. It will take the skills of large and patient companies required over the next 20 years will increase by an order ofto develop an autonomous haulage system. To deal with the magnitude. The upgrading of personal computers across mostrobotics required in a fully automated mine, it requires the sectors of the mining industry represents a major share of thiscombined brainpower of large teams of dedicated research growth. The remainder is driven by the needs of various appli-workers such as those employed at the Rio Tinto Centre cations that target improvements in productivity, cost, quality,for Mine Automation, based at the University of Sydney safety, and reliability, including(Australia). Others will contribute to the development of • Mining and plant scheduling and optimization,advanced sensors. The proving ground for new technology • GPS-based applications,is the mine itself. When all components are proven and the • Automation,system is fully integrated, this template of the autonomous • Finite element analysis/simulation in plant design andmine will be deployed. Components of the system, such as troubleshooting, anddriverless trains, may be deployed earlier. • Adaptive plant control based on predictive models.Driverless TrainRio Tinto has announced that it will automate its iron ore rail- Mine Workersway in the Pilbara region of Western Australia. Within 5 years, Automation may or may not mean fewer workers in the industry.driverless trains will be operating on most of the 1,300 km of It may be that, through automation, fewer workers are employed
  8. 8. 28 SME Mining Engineering Handbookat the mine site or mine output is doubled with the existing work Improving resource and reserve knowledge can provideforce. Regardless of the impact at the mine site, specialist jobs in substantial competitive advantage. It is important to identifydata processing, systems maintenance, electronics, and so forth at an early stage those resources that fit the required extractionwill be created at locations possibly thousands of kilometers profile and are amenable to bulk mining. Ore-body knowledgefrom the mine. These new workers will be housed in high-tech, is critical to the overall design and construction plan. Blockair-conditioned offices or control rooms, a long way from the caves require greater upfront ore-body knowledge, becauseconditions experienced at a mine site. Mine operations in more the final extraction level needs to be planned in detail beforepolitically sensitive regions may well be controlled by workers construction can commence.sitting in an operations center in a neighboring or distant country. Automation and remote operations directly impact Designmine workers, and success in introducing change cannot be Past block cave design has mainly been based on applicationassumed. Much effort needs to go into planning, and com- to weaker rock masses than those proposed today and will bemunication is crucial. The work force must be prepared for required in the future, and, as such, much design work is cur-such change through a well-planned cultural transformation rently based on inappropriate rules and outdated experience.process; if not, barriers to change will be erected. By being Current design methods in block caves are largely based ongiven relevant information, workers must come to understand empirical techniques developed in the 1970s and 1980s, andthat change is necessary for survival. At the same time, they more advanced techniques are still in their infancy. There ismust accept that the ways of the past, while good for their a clear need for a superior understanding of how a rock masstime, will not guarantee future prosperity. Finally, they must will cave and the characteristics of caved material, particu-also understand and accept alternative ways and must embrace larly the fragmentation. As the key driver of block cave mines,the process of change. Although the future of the industry or fragmentation determines bulking and rock flow characteris-their employer may be important, to most workers, income tics that must be understood for optimal mine layout, infra-stability is all that matters, so this must be addressed in any structure, and operational design. Fragmentation determineschange process. Perhaps automation’s most exciting potential, optimal drawpoint spacing, which, in turn, strongly influencesthough, is its power to win a new generation of gifted youth recovery, dilution entry, and mining through the marvels of mechatronics and artificialintelligence (Cribb 2008). Customized Development Design While automation in the mining industry has been lit- Improved characterization of the rock mass through which thetered with many false starts, the challenges facing the industry drift will be developed, via a more rigorous approach to sitetoday demand autonomous solutions. The rewards for being investigation and face mapping, will yield benefits. For exam-at the forefront of automation are great, but the penalties for ple, ground support techniques have not evolved substantiallyinaction are far greater. Mine automation will take leadership, since their inception in early 1970. Better design and productsresources, good planning, cooperation between suppliers and could reduce costs by 10%, saving many millions of dollars.users, and a lot of patience. Such savings could also be achieved in the other caving-type operations. In order to support the substantial levels of invest-UNDERGROUND MINING ment associated with block caves, functional and reliableA number of large mining companies pursue a strategy of design tools are required, which will result in more reliableowning and operating large-scale world-class mines, typically cave the form of large open pits. However, the depth at whichopen-pit mines can be developed is limited. Although larger Reliability in Constructability and Constructionand more efficient trucks will enable open pits to operate to Block caves require large initial capital investment beforegreater depths, it is likely that the economics of strip ratio and revenue is generated. As such, they are similar to civil con-large-scale waste management will be the prime control on struction projects such as road tunnels where revenues aredepth. For example, it is anticipated that an increasing share of not realized until the project is complete. The construction ofRio Tinto’s production, particularly in the copper and diamond three block caves with a capacity of 110 kt/d will requiregroups, will come from underground operations (Clayton • Approximately 16 shafts (8 to 10 m in diameter) 1,500 to2008) and that the majority of investment in the future will be 2,000 m deep with four to five in various stages of con-in the form of large tonnage block cave mines. struction per year over 12 to 15 years, and The challenges of block caving include high capital costs; • Approximately 900 km of horizontal development overlong lead times before revenue generation; and complexity in 12 to 15, construction, and operation. These projects should beconceived of as rock “factories”—mines built to a specified The quality of mine construction is critically important,quality and schedule—and then operated in a predictable man- as repairing and retrofitting the footprint after productionner in terms of production rate, grade, and costs. starts is expensive and interferes with operations. Therefore two significant drivers areKnowledge 1. Time to construct, related to time-cost of money; andThe industry’s block caving experience has driven a number of 2. Quality of construction, related to operating availabilitynew development concepts, which are different from those for and effectiveness.a more typical mine. However, the rate of development needsto increase rapidly. This change in concept requires a change in Because of the long lead times to cash flow and the construc-project definition, planning, and implementation. In particular, tion costs, time to construct the development is vital to a blockan early and deep understanding of ore-body (and waste rock) cave. When projects miss their plan rates of development, thischaracteristics, design, and constructability are critical. seriously impacts the overall project economics.
  9. 9. Future Trends in Mining 29 The importance of construction quality cannot be over- • Development of innovative support system for differentlooked. Lack of attention to quality is a major contributor to excavation systems and ground conditionsslow production start-ups and ongoing operational issues. • Reliable prediction of rock behavior to properly selectQuality is much more critical to block cave operations than to and implement construction technologiesother underground operations because of the costs associated • Use of smart approaches of working with the rock mass towith retrofitting. It is 10 times more expensive to repair after the minimize risks and uncertaintiesfact than to specify fit-for-purpose during design. More impor-tantly, as repairs are undertaken, production delays are incurred. Output Rates If ore bodies are adequately defined and designed, and The goal in mining is to achieve planned output rates in aconstructed to perform to plan, the reliability of production safe and environmentally responsible way. With moves fromwill almost certainly be greatly enhanced. Reliable production open-pit to underground mining as one option for extendingrequires reliable systems and, importantly, automation. The the life of a mine, or with a preference for underground min-construction to plan must include the ability to develop the ing because of its lower environmental impact, output tar-mine to plan. gets will undoubtedly be influential. While this may, at first, seem unreasonable in view of the greater technical difficul-Construction of Underground Infrastructure ties accompanying underground mining, output maintenanceTraditionally, underground development has been regarded as may be crucial to the viability of any mine extension ongoing operating expense. The key driver was the unit cost, The cost of developing a high-output underground mine as anand advance rates tended to be a secondary consideration. This extension of an existing open-pit mine may well be lower thanled to a general acceptance of rates that were below par and the cost of finding and developing a new tier 1 reserve.were substantially less than those achieved in the civil industry. As mentioned, achieving economic output rates via blockReal mine data show that, although equipment technology has caving methods provide numerous challenges. The difficultyimproved, performance has deteriorated. The value of a pro- lies in operating sufficient drawpoints to create the requiredposed block cave mine is heavily influenced by the speed, cost, muck mass and having a materials handling system capableand quality of the development work to put the mine in place. of moving that amount of rock. Here, the development workCurrently, in these circumstances, the key driver is the advance is all related to the mine plan and the layout of the productionrate of the primary access and critical infrastructure, while unit block. For example, preliminary plans for the Grasberg blockcost, although important, is secondary. cave in Indonesia (Brannon et al. 2008) suggest that 1,100 A major portion of future copper and diamond produc- drawpoints are required to deliver an output of 160,000 t/d.tion will be from underground mines. These block cave minesrequire a significant portion of all development to be com- Planningpleted before production can commence. As a result, future When planning an underground mine it is important to haveproduction will require many kilometers of development each detailed knowledge of the ore body, the ore grade, its mineral-year over a 15-year period. ogy, its shape and dimensions, intrusions, and contamination. Today within the mining industry, a single end tunnel is Knowing how a mine will behave during mining operations istypically advanced at an average rate of about 5 m/d, which fundamental. The conversion of an open-pit mine to a blockhas decreased threefold since the 1960s. Over the same time cave mine adds even greater complexity because of the poten-period, equipment performance has increased fivefold and tial for pit failure and the dilution effects that come with ongo-cost per meter of tunnel has increased tenfold. Conversely, the ing deterioration of the pit wall. In addition, the extent of thecivil tunneling industry has seen a steady increase in advance underground mine network inevitably causes higher stressesrates in recent years, and this begs the question as to why min- that must be considered in the mine planning to ensure a suc-ing projects achieve 5 m or less while civil projects achieve cessful transition from open pit to underground. The timing10 m/d. of the transition is not negotiable, because caving can cause Five major reasons contribute to this variance: instability in a pit, so all surface mining activities must cease before ore can be taken from a block cave mine. Such tim- 1. Knowledge: A substantial site investigation is under- ing issues are considered in plans for two major transitions taken prior to developing any civil tunnel. to block cave mines currently being investigated, namely the 2. Planning: Civil tunnels are planned in detail. Grasberg (Indonesia) and Bingham Canyon copper mines. 3. Face size: Larger faces in civil tunnels usually allow The technology used in block cave mines is not new. multi-tasking. What is new is the scale of the mines now being planned, 4. Resources: Civil projects are focused on developing tun- which takes the industry into uncharted territory. For this rea- nels, and more money is spent per meter of development son, the planning process for the conversion of an open-pit in order to achieve schedule. mine to an underground mine is measured in decades rather 5. Technology: A system approach is applied that includes than years. Improved modeling of the mine would deliver different equipment than the conventional mining immeasurable savings in development costs, but to create such drill-and-blast. models, the learning from existing large-scale projects mustFuture significant step-change improvement in the rate of con- first be captured.struction of underground infrastructure will require the fol-lowing initiatives: Bingham Canyon As an example, studies of Bingham Canyon (Brobst et al. • Speed and quality of underground infrastructure con- 2008) and what option to choose (open pit, underground, or struction, including successful implementation of new closure) when the current pit mining operations finish around mechanized excavation technologies and shaft logistics
  10. 10. 30 SME Mining Engineering Handbook2019 provide an interesting insight into the time and effort bodies will require more energy to mine and process. Largerneeded to ensure that all possibilities are considered and the quantities of gangue material need to be brought to the surfacebest option is chosen. The study timeline follows. and then disposed. Against this background, and with higher energy costs and the need to reduce GHG emissions to combat • 1997: study commenced. global warming, efficiency improvements and less-energy- • 2006: order-of-magnitude study complete. intensive processing technologies are essential. Automation, • 2006: prefeasibility study commenced. remote control, improved sensors, and real-time analysis will • 2009: prefeasibility study for expanded open pit due for play a key role in mineral processing developments as they completion. will in other mining operations. • 2013: prefeasibility for block caving methods due for completion. Comminution and Energy Usage • 2019: current operations due to cease. Large amounts of energy are needed to crush and grind rockAs well, the following tests have been conducted during the finely enough for subsequent separation of the minerals ofstudies: interest. Comminution is the most energy-intensive activ- ity in the current mineral concentration flow sheet, consum- • 160 km of drilling ing around 30% to 50% of the total energy requirement. In • 500 unconfined compressive strength tests plants required to grind a very hard ore (nominally Bond work • 500 tensile strength tests index in the range of 15–25 kW·h/t) to finer liberation sizes, • 300 triaxial tests this requirement can be as high as 70% (Cohen 1983). In the • 250 direct shear tests broader perspective, it has been reported that comminutionIn parallel with this, more than 15,000 individual structures activities in the United States account for as much as 1.5% ofalong 44 km of exposed bench in the pit have been measured U.S. total energy consumption (Charles and Gallagher 1982).and logged. This work provides knowledge of the ore body In the context of typically quoted energy efficiencies of lessand surrounds and enables plans to be continually refined. than 5%, comminution is an obvious focus for improvementOne can only imagine the worth of having, at the outset, more for tumbling mills that represent a majority of downstreamdetailed underground knowledge that might be delivered via size advanced, nonintrusive sensing process. Compounding this situation are industry trends toward lower ore grades, which translate into even more intenseOperations comminution processing, hence even higher energy usage toStudies have been conducted into drifting speed (Nord 2008) recover the same quantity of mineral. As ore grade decreases,and the impact of tunnel cross-sectional size and shape, shot process energy requirements rise rapidly, even for the samelength, and the optimum timing of support activities ver- liberation size (Figure 1.3-2).sus activities at the mine face. This knowledge is of great However, the grind size is not a static target. In an effortvalue when linked to productivity and equipment utilization to increase recoveries, today’s grind size target is much finerobjectives. than it was 50 years ago. At one time, a grind size for lead– The key to the future lies, firstly, in developing sensing zinc processing of 70 µm was regarded as fine, whereastechnologies that will provide a better picture of the subsur- today the grind size is more likely to be 7 µm. This is dueface structures, and, secondly, in using advanced computer to the requirement for subsequent processing, includingmodeling (a) to predict the broader impact of mining an ore froth flotation, where finer sizes result in increased recovery.body and (b) to optimize all processes to achieve planned Therefore, despite the development of more efficient grindingoutputs at lowest cost. Because there is only one opportu- mills, there has still been a significant increase in the overallnity in developing and implementing a plan, the uncertainty energy consumption.must be removed during the planning process as much as pos- It may well be that high-pressure grinding rolls (HPGRs)sible. The only certainty is that the growing global demand will become a key technology for hard-rock comminution, pro-for minerals will stimulate changes in underground mining viding high capacity at lower energy intensity. Recent resultsmethods, some of which will be predictable and some will (Anguelov et al. 2008; Michael 2007) suggest that replacingnot be foreseen. semiautogenous grinding mills with HPGRs in a circuit can reduce comminution energy requirements by about 25%.ADVANCED PROCESSINGThe science and practice of mineral processing have been and Flotation and Larger Particlescontinue to be driven by the same internal and external pres- Like comminution, flotation remains a key technology in min-sures that have shaped other facets of the mining industry. At eral processing and one that has seen steady improvementsthe forefront is strong global demand for virtually all minerals over many years. Flotation performance is highly dependentand metals, and this situation is set to continue. on particle size. For best performance, a particle size in the Of greater relevance, given diminishing surface reserves, range of 20 to 100 µm is required. Poor recovery of finethe industry is required to mine ever-deeper deposits and to pro- particles is typically associated with entrainment, whereascess ores of lower quality and more complex mineralogy. This, poor recovery of coarse particles is associated with inertialtogether with increasing requirements for zero environmental forces that prevent the large particles from being recovered.emissions, reduced energy consumption, and sustainability, With increasing pressure to reduce the energy and costs asso-will require even more sophisticated processing methods. ciated with comminution, the desire to increase the particle However, underground mining is traditionally more size in flotation increases. Research will be needed to developenergy intensive than surface mining. Deeper, lower-grade ore improved froth flotation processes that enable these coarser
  11. 11. Future Trends in Mining 31 to yield the same amount of product. New sorting technolo- 50 gies will Grind Size • Dramatically increase the ore grade before processing, 75 µm 40 • Make low-grade ore deposits more economical to mine, Global Warming Potential, 25 µm kg CO2 equivalent/kg Cu 10 µm and 5 µm • Reduce the comminution of gangue minerals. This will 30 significantly reduce the energy consumption per metric ton of product and reduce quantity of tailings generated 20 per metric ton of product, thus reducing associated envi- ronmental and community impacts. 10 New ore-sorting and grinding techniques in the future will enable ores to be processed underground, further reduc- ing waste movement and potentially compounding the ben- 0 0 0.5 1 1.5 2 2.5 3 3.5 efits already mentioned. Underground processing will require Ore Grade, % equipment that is smaller, lighter, and more mobile, possibly made from advanced composite materials.Source: Norgate and Jahanshahi 2007. © CSIRO Australia 2006.Figure 1.3-2  Relationship between ore grade and embodied Heap and In-situ Leachingenergy The ultimate extension of reducing material movement is to leach the ore in the host rock (in place) and not take any waste material to the surface. This technology would be applied toparticles to be separated and to ensure that metal recovery is deep ore bodies that are initially developed for caving usingnot compromised. fully automated methods to ensure high health and safety The trend is toward larger flotation cells to reduce capital standards. The mineralized material is leached in place usingand operating costs associated with flotation (Outotec 2007). acids or solvents chosen according to the metal to be extracted.Cell sizes have increased from around 50 m3 in the early 1990s The dissolved metals are then pumped aboveground andto 300 m3 in 2007, and all signs are that this trend will con- extracted. The acid/solvent works in a closed loop, and thetinue. These large cells present challenges to adequate mixing system would be designed in a way that prevents escape fromand suspension of solids. Larger cells can require higher shear the mining zone. A conceptual approach to in-situ leachingrates to maintain the solids in suspension, which can exas- is shown in Figure  1.3-3. This method is expected to haveperate recovery of coarse particles. The use of computational much lower capital and operating costs and use significantlyfluid dynamics has become an essential tool for understanding less energy. It would also allow for minerals to be extractedthe detailed performance and for designing devices to opti- from harder to reach places and would eliminate the need formize flow profiles in the cell. people to enter the mine altogether, dramatically increasing Because water is becoming a scarce resource in many operational safety.regions, pressure is mounting to manage this resource more In-situ leaching is already used to extract water-solublecarefully. This will undoubtedly serve to stimulate process salts such as sylvite and halite. The application of commer-development wherever water is consumed in the mining cial scale in-situ leaching to sedimentary uranium deposits hasindustry. One likely emerging trend will be the so-called dry also been around since the 1960s. Effectively, the in-situ leachprocessing, where water is replaced by air as the separation process leaves the ore in the ground and recovers mineralsmedia. For example, the rotary air classifier has an action sim- by pumping a leachate solution into boreholes drilled into theilar to that of a conventional wet jig and has been successfully deposit; the pregnant solution from the dissolved minerals isapplied to gold ore processing (Piggott 2000). Another exam- then pumped to the surface. The key to successful leachingple of dry mineral processing is the rotary classifier devel- of uranium is the identification of suitable, below-water-tableoped by Australia’s Commonwealth Scientific and Industrial sedimentary deposits in which uranium is confined in perme-Research Organisation (CSIRO 2009). able rock by impermeable layers. In the future, it is expected that the uranium industry’sMining and Reducing Materials Movement experience will lead to technology developments to enableTwo other trends will affect mineral processing. Mechanical extraction of other metals—for example, copper—in this way.miners using rotating cutters have shown promise in rocks For copper, however, the nature of deposits poses a significantup to 200 MPa, but they produce a quite different size distri- target, because a key requirement is for the ore body to be per-bution than blasting and excavation. The use of mechanical meable to the liquids used. Because porphyry copper depositscutters opens the possibility for sorting before final commi- have low permeability, future challenges include economicnution, which would reduce energy usage significantly. An mine development and sufficient initial fragmentation, as welladded benefit is that mechanical mining and excavation is as subsurface control of the leach solution.more amenable to automation than conventional blasting and In-situ processes could potentially deliver the highestexcavation. goal: a zero environmental footprint. They would enable land New ore-sorting technologies will automatically sense close to or even under cities or in environmentally sensitiveand optimize conditions according to the composition of the areas to be mined without any adverse impact. In the case ofhost rock. This process will reject gangue minerals and hence copper, 99% of the rock mass is left intact and only the valu-significantly reduce the mass of rock required for processing able material is transported to the surface.
  12. 12. 32 SME Mining Engineering Handbook Shaft Solution Flow Paths SX-EW Plant BLS Leaching Turbine PLS Gravity Flow Station PLS Pumping Turbine Station and Sump Injection Level Leach Ore Zone Pump Production Level Pump Vent/Haulage Level Note: BLS = barren leach solution, PLS = pregnant leach solution, SX-EW = solvent extraction electrowinning. Source: Rio Tinto 2003. Figure 1.3-3  In-situ leaching Leaching technology also lends itself to the extraction of Good management is managing a business with an embed-minerals from heaps that, with low head grades, have previ- ded sustainability culture delivered through senior manage-ously been seen as uneconomic to process. Purpose built, fully ment commitment and documented strategies, procedures, andautomated plants would allow extraction rates and yields to be goals, with benefits far outweighing the costs (Skinner 2008).optimized. Solvents would be within closed loops, and heaps These benefits include:monitored and managed with advanced sensor systems. • Reputation, • Access to resources,Energy Supply • Access to talent, andEnergy issues discussed more fully elsewhere in this chap- • Access to capital.ter apply equally here. Low-emission energy sources mustbe pursued and regenerative technologies utilized where pos- Mining companies must put sustainable developmentsible. Of particular relevance for deep underground mines, at the forefront of their operations and future developments.geothermal energy sourced in situ may be used to power all They must work closely with host countries and communi-mining processes. ties, respecting their laws and customs. It is important that In summary, the growth in demand for all minerals will the environmental effects of their activities are kept to a mini-continue for the foreseeable future. If the industry is to keep mum and that local communities benefit as much as possiblepace with this growth, improved mineral-processing tech- from these operations through employment, capacity build-niques must be developed in parallel with improved mining ing, personal development, and poverty reduction (Leneganprocesses. This demand, together with cost, sustainability, 2007). Higher local employment reduces risk to the business.and skills issues combine to drive toward ever larger, auto- The mining industry often operates in remote locations, so itmated mining operations. Mineral processing will be altered makes great business sense to increase the availability of localby the change in scale, particularly the use of ore sorting and goods and services.advanced comminution technologies. However, the growing Society’s expectations of mining companies includescarcity of new high-quality surface deposits is pushing the reducing the footprint of activities so that habitat and speciesindustry toward a greater dependence on underground min- conservation is compromised as little as possible. This meansing. Here, underground sorting and comminution will reduce leaving as much natural variety in place after operations finishthe energy consumed in transporting waste from the mine. as existed before (Slaney 2008). The discipline and manage-Alternatively, in-situ leaching will lead to the elimination of ment tools that underpin sustainable development provide awaste movement and allow extraction to occur with almost mechanism for continually increasing efficiency and produc-zero environmental and community footprint. tivity in the business, generating long-term returns to share- holders. It is this willingness to think in terms of economic,SUSTAINABILITY AND ENERGY social, and environmental sustainability that separates us fromAccording to the United Nations Brundtland Commission, the past and gives us a pointer to the future.sustainable development “meets the needs of the present with-out compromising the ability of future generations to meet Social License to Operatetheir own needs” and covers a diversity of issues that continue Working closely with local communities and indigenousto evolve (Skinner 2008). groups to understand and respond to their concerns and