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By William Gleason

"It is the largest mining exhibition in the world that attracts thousands of attendees from around the world to Las Vegas, NV once every four years. Despite the recent struggles in the mining industry, MINExpo International 2016 promises to be as big as ever. In the following pages, Mining Engineering takes a look what some of the more than 1,800 companies plan to showcase during the three-day exhibition.CaterpillarCaterpillar will support MINExpo 2016 with an exhibit showcasing machines, technology, expertise and practical knowledge that miners can apply to help address their cost, productivity and efficiency challenges in today’s mining environment.Caterpillar will once again occupy the largest space at the event and will showcase both surface and underground machines, but the talk at the booth will focus on how Cat technology and know-how combines to help mining operations address and solve the issues that are most important to them. The main stage in the exhibit will feature presentations describing how mining companies, Cat dealers and Caterpillar work together to improve operations.“The challenge for all in the mining industry now is to optimize operations — to drive costs down while creating sustainable businesses that can weather downturns,” said Caterpillar Resource Industries group president Denise Johnson. “We believe that through our expertise and the knowledge of our dealers —combined with innovative technologies and our growing data analysis capabilities — we can help them not only survive, but thrive in these challenging times.” Johnson was selected by the National Mining Association (NMA) to chair MINExpo 2016. “Chairing this show is a great honor, and it’s a testament to Caterpillar’s partnership with this critical industry,” she said. “We’re proud to be a long-time supporter of the NMA, and we are excited to participate in another MINExpo. It’s an opportunity for us all to learn from each other how to increase productivity, control costs and improve overall operations.”Surface mining displays. The surface mining section of the Caterpillar exhibit will showcase the new MD6420C rotary drill. This is autonomy ready and optionally equipped to leverage the safety and productivity benefits of Cat MineStar Terrain. This high-precision drill management system optimizes utilization and improves drilling and blasting operations by accurately guiding the operator and improving precision of hole placement and drilling depth — and the next step is fully autonomous operation, Command for drilling. The third-generation drill incorporates proven Cat components throughout for superior reliability and durability."

Sep 1, 2016

By Bob Miller

"All industries have parts and equipment that are exposed to some type of destructive wear. Hardfacing is a cost-effective tool that will minimize wear and increase service life. At first glance, hardfacing can be confusing and troublesome. In reality, it is not.Postle Industries, a manufacturer of hardfacing products, has found that the 22 answers to frequently asked questions may help operators select hardfacing products that are most appropriate for their application. The first 10 questions are addressed in these pages, the full list can seen at Mining Engineering online under the Web-Only Content section.1. What is hardfacing?Metal parts often fail their intended use not because they fracture, but because they wear by abrasion, impact, metal-to-metal contact or some other form of wear, which causes the parts to lose dimension and functionality. Hardfacing, also known as hard surfacing, is the application of a buildup or wear-resistant weld metal onto a part’s surface by means of welding to extend the life of the part. The weld metal may be applied as a solid surface or in a pattern, such as a waffle pattern, herringbone or dot pattern, etc.Hardfacing is becoming increasingly important for many industries to protect equipment that is exposed to wear and abrasion including parts used in mining, earthmoving and construction, oil and gas drilling and steel making and forging. Extending the life of wear parts can save thousands of dollars and improve productivity. Hardfacing can be used to recondition parts that have already been exposed to wear and have lost their useful life, or used in the manufacture of new parts to improve their life before they are put into service.There are three main types of hardfacing applications:• Build-up or rebuilding.• Hardfacing or overlay.• A combination of build-up and overlay.2. What base metals can be hardfaced?Carbon and low-alloy steels with carbon contents of less than 1 percent can be hardfaced. Medium carbon and low-alloy steels are very common since they provide higher strength than mild steels and better abrasion resistance. High carbon alloys may require a special buffer layer.The following base metals can be hardfaced:• Stainless steels.• Manganese steels.• Carbon and alloy steels.• Cast irons.• Nickel-base alloys.• Copper-base alloys."

Aug 1, 2016

By C. C. Clark, D. J. Benton, J. B. Seymour, L. A. Martin

"The U.S. National Institute for Occupational Safety and Health (NIOSH) is conducting research on jackleg use and related accidents in underground metal mines. This paper provides an analysis and overview of jackleg drill usage, accidents, operational characteristics and alternatives, based on information from injury reports, legacy research, stakeholder input and published literature. The results indicate that jackleg drills are involved in more groundfall accidents in underground metal mines than any other drill, and jackleg-drill-related injuries are most prevalent at the face in the course of installing initial ground support. Practical mechanized alternatives to jackleg drills for drilling and bolting under incomplete support in narrow underground openings have not yet been realized. Small, versatile mechanized bolting equipment needs to be developed to address jackleg-drill-related accidents and improve safety at mines where jackleg drills are being used. IntroductionJackleg drill is a generic name for a handheld, rotary, percussion rock drill equipped with an attached reaction leg to provide stability and thrust (Fig. 1). All of the drill and leg controls are located near the operator’s handle at the rear of the head portion of the drill. Jackleg drills are classified according to the bore size of their pneumatic pistons, which normally range from 6.03 to 8.26 cm (2.375 to 3.25 in.) (Kurt, 1982; Clark, 2012). Jackleg drills typically weigh 46.7 kg (103 lb), but the weight can approach 54.4 kg (120 lb) after being fitted for operation with drill steel and air and water hoses (McKibbin and Clark, 2001). In underground mines, jackleg drills are commonly used to drill 3.8-cm (1.5-in.) diameter holes up to 1.83 m (6 ft) deep in rock."

Aug 1, 2016

By J. D. Noll, J. A. Organiscak, A. B. Cecala

Significant strides have been made in optimizing the design of filtration and pressurization systems used on the enclosed cabs of mobile mining equipment to reduce respirable dust and provide the best air quality to the equipment operators. Considering all of the advances made in this area, one aspect that still needed to be evaluated was a comparison of the efficiencies of the different filters used in these systems. As high-efficiency particulate arrestance (HEPA) filters provide the highest filtering efficiency, the general assumption would be that they would also provide the greatest level of protection to workers. Researchers for the U.S. National Institute for Occupational Safety and Health (NIOSH) speculated, based upon a previous laboratory study, that filters with minimum efficiency reporting value, or MERV rating, of 16 may be a more appropriate choice than HEPA filters in most cases for the mining industry. A study was therefore performed comparing HEPA and MERV 16 filters on two kinds of underground limestone mining equipment, a roof bolter and a face drill, to evaluate this theory. Testing showed that, at the 95-percent confidence level, there was no statistical difference between the efficiencies of the two types of filters on the two kinds of mining equipment. As the MERV 16 filters were less restrictive, provided greater airflow and cab pressurization, cost less and required less-frequent replacement than the HEPA filters, the MERV 16 filters were concluded to be the optimal choice for both the roof bolter and the face drill in this comparative analysis case study. Another key finding of this study is the substantial improvement in the effectiveness of filtration and pressurization systems when using a final filter design.

Aug 1, 2016

By Mark J. Zdunczyk

"The term “aggregate” has a number of definitions depending primarily on the use of the material. Aggregate in some context is sand, gravel, crushed stone, slag or other material of mineral composition used in bituminous and portland cement concrete, mortar, plaster, railroad ballast, filter beds and a variety of other uses where aggregates can be utilized.Of the natural aggregates, crushed stone is widely used for most construction purposes. Crushed stone can be mined from a variety of rock types such as limestone, dolomite (dolostone), granites, and granitic type rocks, basalt, gabbro (trap rock), sandstones, schist, marble, gneiss, quartzite, rhyolite, as well as other rock types. The U.S. Geological Survey (USGS) breaks down the rocks by type sold as follows: limestone, dolomite, marble, calcareous marl, shell, granite, trap rock (basalt, diorite) sandstone/quartzite, slate, volcanic cinder and scoria and miscellaneous stone.In 2015, the USGS estimates that 1.32 Gt (1.45 billion st) of crushed stone were produced in the United States. The volume of crushed stone produced, and the numerous mines that produce it make the crushed stone industry the largest mining industry in the United States. The five leading states for production of crushed stone in 2015 were Texas, Pennsylvania, Missouri, Florida and Ohio. The size of the first two states certainly helps in output because of the large market area. The remaining states benefit from being able to barge along rivers to outside markets in adjoining states. Georgia producers rail large amounts of granitic aggregate to Florida and adjacent states devoid of crushed stone aggregate, especially skid resistant aggregate (aggregate used on the top course of asphalt roads)."

Jul 1, 2016

By Gordon I. McPhail

"El presente texto señala un método de conservación del agua y diseños de drenajes para el control de ARD (Drenaje Ácido de Rocas). El método fue aplicado en el desarrollo de un proyecto aurífero en Argentina, donde dada la cercanía de la mina con el pueblo, se eliminó el uso del cianuro y se empleó el procesamiento off-site que contó con una gran cantidad de escenarios de desarrollo viables. Este planeamiento considera un proceso integral de molienda, concentración y relaves que reemplaza las instalaciones para el almacenamiento de relaves (TSF) como entidades independientes. Así también cuantifica las compensaciones hechas entre los beneficios y efectos sociales, económicos y ambientales. "

Jul 1, 2016

By Daniel M. Flanagan

"Editor’s note: Each year, Mining Engineering features an industrial minerals review. Several people put in a fair amount of time in developing the material for this issue, all the while doing their own jobs. Thank you to the industrial minerals annual review editor, to the Industrial Minerals & Aggregates Division technical committee chair and vice chairs, and to the authors of the individual commodity profiles. Jim Norman, member SME, of Tetra Tech, is the industrial minerals annual review editor.Joe Garska, member SME, of Imerys, is chair of the Industrial Minerals &Aggregates Division’s Technical Committee.The technical committee vice chairs include:• Hyunjung Kim, member SME, of Chonbuk National University, agricultural materials.• Xihui Lin, member SME, of Kemira, ceramics and refractory materials.• Nikhil Gupta, member SME, of Virginia Tech, chemical raw materials.• Adam Rodriquez, member SME, of Penn State, construction aggregates.• LeDeana Roberts, member SME, of Imerys, fillers and pigments.• Harsha Kolla, member SME, of ChemEOR, sorbents, filters and process aids.• Edgar Blanco, member SME, of FLSmidth, specialty minerals.Their help makes possible this July industrial minerals issue. On behalf of ME readers, the editors thank them.During the past 25 years, U.S. ball clay production (the quantity sold or used by domestic producers) increased from 788 kt (869,000 st) in 1990 to an alltime high of 1.31 Mt (1.44 million st) in 2003 (Fig. 1). Housing construction within the United States, a leading market for ball clay-based ceramics and sanitaryware, began to decline in 2005, which resulted in a considerable decrease in sales of ball clay that continued through the 2008-2009 economic recession. After bottoming out at 831 kt (916,000 st) in 2009, ball clay production steadily increased through 2015 (Fig. 1). Estimated sales in 2015 were 36 percent higher than those in 1990 and 18 percent lower than those in 2003.Four companies (H.C. Spinks Clay Co., Imerys S.A., Old Hickory Clay Co., and Unimin Corp.), mined ball clay in five states during 2015. An estimated 1.7 Mt (1.18 million st) of ball clay valued at an estimated $47.5 million was sold or used by U.S. producers, a 4-percent increase from 1.03 Mt (1.14 million st) valued at $45.2 million in 2014. Approximately 65 percent of total ball clay production was air-float, 25 percent was crude or shredded and 10 percent was water-slurried"

Jul 1, 2016

By Mark J. Zdunczyk

"Frac sand is industrial silica sand much like glass, foundry, filtration and blast sand. The sand must meet certain specifications set forth by the industry that consumes the product. The production and consumption of frac sand has experienced record growth in the last 10 years because of new oil and gas drilling, new horizontal well drilling, multi-stage fracturing and the stimulation of older wells that have little or no production. Frac sand is needed to “prop open” the fractures in the rock reservoirs to allow oil and gas to flow out more freely.According to the U.S. Geological Survey (USGS), the estimated production of frac sand in 2015 was 71 percent of the total production of industrial silica sand or 67.4 Mt (74.3 million st). This is a decrease of about 12 percent from 2014. However, the silica sand industry and other industry sources estimate only 50 Mt (55 million st) of frac sand were produced in 2015. In recent years both the USGS and industry studies have been very close in estimating the production of frac sand but with the recent downturn in frac sand production, perhaps, reporting to the USGS was not as accurate. These discrepancies may be that the USGS statistics are based on voluntary reporting by the industry and some companies report their approximate production, others may not. It is always difficult to obtain accurate production figures of any industrial mineral or construction aggregate operation as most companies tend to keep those figures somewhat confidential. It is certainly accurate to report that the production of frac sand had decreased since the last quarter of 2014 and through 2015. The oversupply of oil and natural gas has led to this decline in frac sand usage. Oversupply has idled drilling rigs and well completion activities. World Oil Magazine reports that 2015 was the worst year for rigs in a quarter century. The only wells being completed are those that have contract agreements to do so, others have been capped. Very few new wells are being drilled. Since about 98 percent of well completion is sand and water, the sand supply has caught up with the demand. There are some bright spots in the “oil patch” as the Permian Basin in Texas and the Woodford Shale in Oklahoma have kept pace somewhat with drilling and completion. It has been reported that the frac sand producers in the Brady-Voca, TX area are producing to nearly capacity. The northern frac sand producers like those in Wisconsin, Illinois and Minnesota are feeling the downturn because of the cost of shipping sand to these moderately active basins and plays. The “rule of thumb” is that freight is 2/3 and sand is 1/3 the cost."

Jul 1, 2016

By William Gleason

"In a time that seems to be dominated with nothing but bad news coming from the mining industry, there is a success story that has been quietly happening in Southwestern Wyoming for more than 60 years, and it is one that is likely to continue for many decades to come.Beneath the wind swept high desert plains of Sweetwater County, WY, about 32 km (20 miles) west of Green River, lies the Green River Basin where five companies, including Tata Chemicals North America (TCNA), are mining the world’s largest known deposit of trona and, in turn, are collectively producing 15.3 Mt/a (17 million stpy) of soda ash.“We have a long-term growth story that has been, and will continue to be a steady earner for many years to come,” said J. Martin Keighley, managing director of TCNA who has been in charge of the mine, formerly known as General Chemical Industrial Products Inc., for Tata Chemicals for about three years.According to the U.S. Bureau of Land Management (BLM), Keighley is safe with his prediction of future success. The BLM estimates that there are enough reserves in the Green River Basin to last another 2,000 years. Currently, four trona beds in the Green River Basin are being mined and in all, there are 25 major trona beds that occur within the Wilkins Peak Member of the Upper Eocene Age Green River Formation. The trona deposit as a whole covers about 2,500 km2 (1,000 sq miles) within the Green River Basin.And imagine, this economic mainstay in the region was discovered accidently.Prior to 1948, soda ash, the salable commodity that comes from trona and is used in a host of products including glass and detergent, was produced synthetically. In 1938, an oil and gas exploration team working in the Green River Basin came away with a find that would change the soda ash industry and the physical and employment landscape of southwestern Wyoming forever. Within 10 years, the communities of Green River and Rock Springs, which were built largely on the back of coal mining and railroads, had another commodity beneath their feet."

Jul 1, 2016

By H J. J Boshoff, A J. Karrasch

Mine planners frequently face the challenge of mitigating the impact of climatic events on mining operations, such as floods and droughts. Specific water management infrastructure can be implemented to meet operational requirements in response to these events. However, the effect of flood protection, for instance, may reduce the resilience of the site to drought. The probability and duration of unfavourable climate sequences significantly influences the net present value (NPV) of implementing specific water management infrastructure.Good life-of-mine planning will consider the incremental development of the project, and provide staged development plans. Water management infrastructure and the timing of implementation are facets of this process.CITATION:Boshoff, H J J and Karrasch, A J, 2016. A decision-making framework for water supply and flood protection options in net present value terms, in Proceedings Life-of-Mine 2016 Conference , pp 196–199 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

By G R. Hancock, D Verdon-Kidd, M J. Saynor, J B. C Lowry, T J. Coulthard

The ability to simulate the stability of post-mining landscapes over time scales ranging from decades to millennia is a critical element in the assessment of closure designs for uranium mines. Landscape Evolution Modelling (LEM) technologies provide a means to simulate and assess the long-term geomorphic stability of a conceptual rehabilitated landform for periods of thousands of years. However, a major issue with simulations derived from long-term modelling are the limitations associated with the data inputs. Specifically, simulations which utilise historic rainfall data only represent the variability of rainfall events that have occurred over a relatively short period. Consequently, these simulations run the risk of not accounting for the full range of rainfall variability that might be expected over an extended period of up to 10 000 years. Therefore, for this study a probabilistic approach was adopted to generate a stochastic synthetic rainfall data set to produce a series of unique rainfall scenarios, each representing a simulated period of 100 years. Importantly, utilising such an approach allows uncertainty in predictions to be better accounted for and provides a range or probability of likely outcomes.In this study, the effect of ten individual rainfall scenarios are assessed in terms of their impact on the predicted erosion and denudations rates produced by the CAESAR-Lisflood LEM for a conceptual rehabilitated landform of the Ranger Uranium Mine (RUM) in the Northern Territory of Australia, focusing on the Corridor Creek catchment (Figure 1). While legislation requires this site to be erosionally stable for at least 10 000 years (Commonwealth of Australia, 1987), here the focus is on the first one hundred years of landscape evolution, as this is the period in which erosion is expected to be higher, with limited vegetation cover or pedogenic development in the initial decades after rehabilitation. It is also the period where the drainage pattern is set.CITATION:Lowry, J B C, Verdon-Kidd, D, Hancock, G R, Saynor, M J and Coulthard, T J, 2016. Application of synthetic rainfall data to long-term modelling of a rehabilitated landform, in Proceedings Life-of-Mine 2016 Conference , pp 75–79 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

By J A. Meadows, M G. Annandale, G Castelain

Bauxite mining on Cape York Peninsula (CYP) commenced in the early 1960s in the region surrounding the town of Weipa. Rio Tinto Alcan (RTA) operates its bauxite mines on the homelands of 11 Indigenous Traditional Owner groups. The mining activity currently operates under three Aboriginal Agreements including an Indigenous Land Use Agreement – the Western Cape Communities Coexistence Agreement (WCCCA) – which provides RTA with access to the land in return for a range of benefits to the Traditional Owners, including employment, training, royalty payments and future relinquishment of the land (Klimenko and Evans, 2009). Despite reports of some ‘good progress’ in meeting the terms of the WCCCA (Klimenko and Evans, 2009, p 5), many of the region’s Traditional Owners remain dissatisfied. Two key areas of Indigenous community concern are the current premining management practices and the outcomes of post-mining landscape rehabilitation efforts.CITATION:Annandale, M G, Castelain, G and Meadows, J A, 2016. Sustainable mining – indigenous community benefit, in Proceedings Life-of-Mine 2016 Conference, pp 173–175 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

By T van Niel, M Trefry, B Baker, I Rea, A Hawdon, D McJannet, D Boadle, R Fandrich, A Littleboy

Many open cut mines extend to depths well below the natural water table level with constant dewatering required to maintain operations. When mining activities cease the groundwater starts to fill the void and pit lakes form. The resultant pit lake is directly connected to the surrounding water table and understanding the hydrological and chemical evolution of these lakes is important for minimising environmental impacts. In Western Australia alone there are currently 1800 mine voids and more than 150 mines operating below the water table (Johnson and Wright, 2003). In conjunction with BHP Billiton Iron Ore, CSIRO has been undertaking research to measure and model rates of evaporation from pit lakes in the Pilbara region of Western Australia. Extreme high temperatures and low humidity ensures that this region experiences the highest evaporation rates in Australia.CITATION:McJannet, D, Hawdon, A, Boadle, D, Baker, B, van Neil, T, Littleboy, A, Trefry, M, Rea, I and Fandrich, R, 2016. Measurements and modelling of evaporation from abandoned mine pit lakes, in Proceedings Life-of-Mine 2016 Conference, pp 106–109 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

By K Brand, M J. Ind, M Rynhoud

Water management at a tailings storage facility (TSF) presents one of the major risks to the safe performance of the facility. International and domestic dam safety guidelines assess a dam’s hazard category based on the consequences of a dam failure and the subsequent downstream damage to the environment and communities.Often a rigorous risk assessment is undertaken during the design stages to identify and control hazards associated with water management through life-of-mine (LOM) phases. However, as experienced during the recent downturn in commodity prices, early closure of a mine can occur rapidly and unexpectedly. Although guidelines such as the Australian National Committee on Large Dams Incorporated (ANCOLD) recommend that one of the key objectives of integrated TSF planning is to ‘plan all phases of a tailing dam’s life to ensure adequate storage capacity including early closure ’ (Australian National Committee on Large Dams Incorporated (ANCOLD), 2012) this is often overlooked by owners who are focused on fulfilling the mine’s potential and early closure is not on their radar.CITATION:Ind, M J, Rynhoud, M and Brand, K, 2016. Life-of-mine spillway strategy – managing risk associated with surface water at a tailings storage facility, in Proceedings Life-of-Mine 2016 Conference, pp 209–211 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

By J Purandare, D Murdoch

The goal of the life-of-mine plan is to ensure that while the site is left safe, stable and non-polluting, the landscape is such that optimal use can be made of the site post-mining and closure. However, in the face of evolving shareholder expectations and the current international economic climate, numerous mines are ceasing operations and moving into a care and maintenance phase. These changes bring with them a high degree of community concern, not only about the potential legacy of closed operations, but also those mines that continue to operate.While mines across Australia are committed from the earliest planning stage to develop clearly defined post-mining land use and landform objectives, broader expectations related to these objectives may change and evolve during the life of the operation. This is especially the case where a mining operation has a project approval where the land use objectives are aligned to land capability and land use commensurate to that which occurred premining. CITATION:Murdoch, D and Purandare, J, 2016. Optimising land for beneficial use during and after mining, in Proceedings Life-of-Mine 2016 Conference, pp 166–167 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

By S L. Simpson, J Waworuntu, B M. Angel

"The Batu Hijau copper/gold mine, operated by PT Newmont Nusa Tenggara, is located in the south-western part of Sumbawa Island, Indonesia, and is situated ~10 km from the south coast at an altitude of ~450 m above sea level. The mine became fully operational by year 2000 and processes approximately 120 000 t of ore per day that contain an average of 0.53 per cent copper and 0.4 per tonne (g/t) gold. Tailings management at the mine includes a deep-sea tailings placement (DSTP) system that discharges tailings through a pipeline via an outfall located at a depth of 125 m at the head of the submarine Senunu Canyon (Figure 1).The environmental impact assessment undertaken prior to approval of the DSTP evaluated both on-land tailings storage facility (TSF) and DSTP options for tailings management. Negative attributes of the on-land TSF included removal of approximately 2300 ha of forest/agricultural land, the potential relocation of >2000 people from their communities, the high average annual rainfall (>2500 mm) and potential for earthquakes presenting challenges for water management and creating a long-term risk of failure. The final choice and Indonesian Government’s approval of DSTP was also influenced by the close proximity of the deep submarine canyon to the mine. The Batu Hijau mine is one of the larger examples of DSTP in the world and deposits tailings at the greatest depth. The depth of the main canyon increases to >2000 m within 20 km of the coast, and to >3000 m approximately 50 km from the coast.The DTSP at Batu Hijau must comply with an environment management plan (EMP) and environment monitoring plan of permit stipulation that approved its commencement in 2000; updated in 2010 and 2015. The environmental management objectives were to avoid impacts to highly productive components of the ecosystem such as coral reefs, mangroves, surface waters and fisheries, and confinement of impacts to areas of low biological productivity. In the vicinity of the DSTP outfall and within the Senunu Canyon, the management plan predicted significant adverse impacts from the DSTP on the marine ecosystem in the form of: reduction in sea water quality due to elevated turbidity and dissolved copper concentrations burial of benthic organisms a reduced habitat for demersal fish.Recovery of the pelagic and benthic ecosystem to preoperating conditions was predicted to occur within the first two years after operations cease. The CSIRO has performed due diligence studies to independently verify compliance with permits and evaluate new monitoring objectives (Apte et al, 2004; Simpson et al, 2010; Angel et al, 2015), and has performed assessments of environmental monitoring data on the tailings footprint and ore stockpile processing against the above environmental objectives (Simpson and Angel, 2015).CITATION:Angel, B M, Simpson, S L and Waworuntu, J, 2016. Long-term monitoring and targeted assessments to improve management of mine wastes – the Batu Hijau project, in Proceedings Life-of-Mine 2016 Conference, pp 81–84 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 28, 2016

By P Swart, A Fletcher, P D. Erskine

Glencore Coal Assets Australia (GCAA) operates five coalmines in Queensland and has rehabilitated thousands of hectares of mined land across these sites. Accordingly, GCAA seeks to continually improve rehabilitation outcomes over time and work towards progressive rehabilitation sign-off. The ultimate test of rehabilitation success is the attainment of an agreed land-use target, whether for biodiversity conservation or some type of agricultural production, and the ability of the rehabilitated landscape to resist degradation and retain desired functions (eg biodiversity protection or grazing productivity). However, success must be based on documented evidence that can demonstrate adequate progress towards rehabilitation targets and is assessed at appropriate intervals. To assist this task, a stepwise decision guide for the GCAA monitoring program was developed to ensure consistent monitoring data is collected across the range of sites. This presentation will discuss some of the processes that were followed to allow GCAA to identify appropriate metrics to assess rehabilitation success efficiently over thousands of hectares.CITATION:Erskine, P, Fletcher, A and Swart, P, 2016. Preparing for progressive mine rehabilitation sign-off in Queensland, in Proceedings Life-of-Mine 2016 Conference, pp 148–150 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

By P D. Erskine, A Hine

The current Queensland Government’s rehabilitation guidelines for post-mining landforms present a hierarchy of preferred outcomes for different areas within the mine site (see Figure 1). Within all areas, restoration of a ‘natural’ ecosystem is clearly prioritised as the preferred end land use, although it is not a mandatory practice. Beyond the official guidelines, there is also an implied preference for renaturalisation echoed in most environmental impact assessments and closure plans (Lamb, Erskine and Fletcher, 2015). In practice, however, ecosystem restoration does not extend to construction of a realistic topographic form, largely rejecting the ‘natural’ aesthetic implied by ecosystem restoration in favour of adopting a functional aesthetic in deference to standard engineering criteria.This presentation argues that the established disconnection between actual and implied landform aesthetics is indicative of a wider problem around end landform planning. It contends that such disconnects are the result of the impact of competing ‘ways of seeing’ (Bradley and Kearney, 2007) the same landscape, and reflect the struggle between, and inclusion of, these differing perspectives within the planning process itself. We propose that recognition of the complexity of landscape perceptions is key to improving post-mining landscape outcomes, and the misalignment between land use values and landscape aesthetics can be addressed by establishing an overarching framework for landscape preferences. As such, we outline the reality of stakeholder landscape preferences, and present a critical response to current planning practices within the life-of-mine (LOM).CITATION:Hine, A and Erskine, P, 2016. Recognising and integrating stakeholder landform expectations into life-of-mine planning, in Proceedings Life-of-Mine 2016 Conference, pp 154–157 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

By J Heyes, G A. Maddocks, R J. Stewart, G D. Corder

Mining is an international business and vital contributor to national and global economies. It depends on the trust and confidence of investors and stakeholders for its financial and operational well-being (Committee for Mineral Reserves International Reporting Standards (CRIRSCO), 2016). The Social Licence to Operate (SLTO) is an increasingly multifaceted and multistakeholder risk that can impact investment decisions. Community challenges to broader political and economic decisions have given rise to protest delaying or stopping projects or closing mines and has led to loss of life (Ernst and Young, 2016). Some governments are now giving greater powers to stakeholders to make the final decision on approving mining and metals activities (EY, 2016). With billions of dollars in project investment at stake, ongoing engagement, collaboration and effective communication with stakeholders is crucial and mutually beneficial solutions are increasingly expected (EY, 2016). It is therefore essential that the industry communicates the risks (and opportunities) associated with investment effectively and transparently in order to earn the necessary level of trust with investors and stakeholders to underpin its activities (CRIRSCO, 2016). Despite this need, investor and stakeholder trust in the sector has eroded in recent years.CITATION:Maddocks, G A, Corder, G D, Heyes, J and Stewart, R J, 2016. The social licence to operate and drivers for change – resource reporting and mine material characterisation, in Proceedings Life-of-Mine 2016 Conference, pp 183–187 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

By G R. Hancock, J B. C Lowry, T J. Coulthard

A reconstructed landscape may exert long-term influences on its surrounds and behave in ways that may not be predictable given uncertainties regarding climate, soil and vegetation interactions (Evans, 2000). In recent years, computer-based landscape evolution models (LEM) have been used to assess potential and existing mining landscapes and their long-term geomorphic behaviour (Hancock et al, 2007; Hancock, Lowry and Coulthard, 2015; Tucker and Hancock, 2010).In this paper, we focus on the evolution of post-mining landforms, which are designed to include burial or encapsulation of mine-impacted areas and materials, including tailings, drains, spoil tips and other industrial architecture (Figure 1). At the Ranger Uranium mine in the Northern Territory of Australia, low-grade uranium ore, tailings, brines and other mine wastes will be buried at depth in the areas of the former pits and tailings storage facilities.The use of LEMs to predict long-term landscape evolution has several issues. These include that model predictions are based on the calibration and parameterisation of the model carried out using values determined from present day, or recent surface conditions. Furthermore, there is also the question as to how subtle perturbations or roughness on the DEM surface can produce alternative model results by randomly varying the elevations of the DEM surface.In this study we examine the effect on sediment transport rates and geomorphology for a proposed rehabilitated landform using multiple landscape realisations with increasing magnitudes of random changes in the DEM using the SIBERIA LEM (Willgoose, Bras and Rodriguez-Iturbe, 1991).CITATION:Hancock, G R, Coulthard, T J and Lowry, J B C, 2016. Use of landform evolution models to assess uncertainty in long-term evolution of post-mining landscapes, in Proceedings Life-of-Mine 2016 Conference, pp 67–70 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016