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By Qinbo Cao, Qianshan Peng, Heng Zou, Xingcai Yu

In this work, a new flotation strategy was proposed for the flotation of rutile. In this strategy, rutile was activated by Pb(NO3)2 and then floated with amyl xanthate (AX) as a collector at pH 8. Pb(OH)+ was the dominant lead species in the solution at pH 8 and is believed to be the major species reacting with the rutile surface. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) study revealed that the lead activation products were well distributed on the rutile surface, and AX− could further bind with the Pb atom on the Pb-activated rutile surface. In this regard, the Pb-activated rutile could be floated by AX. Furthermore, X-ray photoelectron spectroscopy (XPS) analysis indicated that Pb(OH)2 was generated on the Pb-activated rutile surface. The electron transfer during the adsorption of the AX− on the Pb-activated rutile surface was also investigated by XPS analysis.

By S. F. Diehl

Weathered mine waste consists of oxidized primary minerals and chemically unstable secondary phases that can be sources of readily soluble metals and acid rock drainage. Elevated concentrations of metals such as Cd, Cu, Fe, Mn, Ni, Pb, and Zn are observed in deionized water-based leachate solutions derived from complex sedex and Cu-Pb-Zn mine wastes. Leachate (USGS FLT) from the Elizabeth mine, a massive sulfide deposit, has a pH of 3.4 and high concentrations of Al (16700 ug/L), Cu (440 ug/L), and Zn (8620 ug/L). Leachate from the sedex Faro mine has a pH of 3.5 and high concentrations of Al (2040 ug/L), Cu (1930 ug/L), Pb (2080 ug/L), and Zn (52900 ug/L). In contrast, higher-pH leachates produced from tailings of polymetallic vein deposits have order of magnitude lower metal concentrations. These data indicate that highly soluble secondary mineral phases exist at the surface of waste material where the samples were collected. Sulfide minerals from all sites exhibit differential degrees of weathering, from dissolution etched grain rims, to rinds of secondary minerals, to skeletal remnants. These microscale mineral-dissolution textures enhance weathering and metal leachability of waste material. Besides the formation of secondary minerals, sulfide grains from dried tailings samples may be coated by amorphous Fe-Al-Si minerals that also adsorb metals such as Cu, Ni, and Zn.

Jan 1, 2011

By Marcus A. Wiley, Gregory Abramov

Borehole mining (BHM) is a remotely operated method of extracting rock material through boreholes by high-pressure water jets. Figure 1 illustrates a BHM tool and fluids circulation. The tool consists of at least two pipes, one for pumping down high-pressure water, the second for delivering slurry to the surface. This article reviews the BHM process. It discusses current and new applications for borehole mining and help the readers determine if BHM is applicable in their situations. Previous articles in ME about BHM explained either a particular project (ME, April 2001, pp. 33-36) or a newest patent in this area (ME, March 1991, pp. 313-318). However, neither one provided an overview on the modern BHM technology.

Jan 1, 2004

By G. S. Takenaka

When Bridger Coal Company transformed their operations from surface mining to an underground longwall operation their plans included not only the addition of new mining equipment but also surface fans for a blowing (supply) air ventilation system. The original system concept included a propane gas fired air heater to preheat the intake air during cold weather and a dual parallel fan and duct system. One fan operated to ventilate the mine while the other fan was for stand-by emergency operation. Equipment proposals were submitted in March, 2005 based on the dual parallel fan system. Discussions conducted during the equipment selection process revealed that several alternative system design concepts were available. The alternative concepts included innovation features that not only saved space and cost but also reduced operating expense as well. Many of the features were incorporated into the final design of the system. A comparison of the original system concept and final installation design are presented in the paper in addition to details of the features and the derived benefits.

Jan 1, 2009

By Paul D. Klipfel

Introduction Mineral exploration interest, principally for gold, in the south-western Pacific has surged to new proportions. This is primarily due to the application of epithermal exploration concepts in the Australian-Oceana region. Other factors that have contributed to the high level of exploration interest include governmental policies supportive of mineral exploration, along with relative ease of tenure access and a relatively short bureaucratic process. This paper highlights exploration and development activities in the North Island of New Zealand, Fiji, Vanuatu, the Solomon Islands, and Papua New Guinea (Fig. 1). It provides a framework to understand the overall recent enthusiasm that has been brought to the south Pacific by explorationists. Through these recent developments, it is clear that the south Pacific region will become a significant gold producing area and thereby worthy of attention and study. Papua New Guinea alone is the free world's seventh largest producer (Table 1). And, with the addition of production from deposits presently being developed, this status is likely to be raised. History Gold was first noted on various Pacific islands in the late 1500s by Spanish explorers. They thought they had reached the legendary King Solomon mines. Since then, the history of prospecting in the southwest Pacific has coincided with the colonization of the region. Settlers in New Zealand extensively mined alluvial and lode gold deposits starting in the 1850s. The spread of European colonization to the more remote Pacific islands from 1880-1940 was accompanied by varying degrees of prospecting activity by planters, traders, and settlers. Some were successful, others may have been successful, but never returned due to hostile indigenous peoples or disease. In general, records of such prospecting activity are meager and exploration leads are, in some cases, gained through local village folk memory. Most early discoveries were alluvial finds. These led to placer operations, particularly in New Zealand, the Solomon Islands, and Papua New Guinea. Continued prospecting located lode deposits such as the Morobe Gold-field of Papua New Guinea, the Coromandel Peninsula of New Zealand, and the Emperor of Fiji. Some areas were prospected thoroughly. Yet others, such as Vanuatu, remained relatively unexplored until the present exploration surge began. During World War II, interest in minerals was diverted. It was renewed significantly until the middle 1960s and early 1970s when regional porphyry copper exploration was conducted.

Jan 10, 1987

Recent advances in GPS, machine guidance technology and telemetry allow an unprecedented level of control of surface mining operations. GPS technology can now locate the bucket of a shovel or the blade of a dozer within 50mm (2 inches).Some of the outcomes possible are: precise selective mining – even when the ore is visually indistinguishable from waste: tracking grade and tonnage of every ore parcel through the mine: real time productivity monitoring: detailed post accident safety analysis: tracking the movements of every piece of equipment. This paper will consider the contribution that GPS based machine control systems can make to ensuring that surface mining projects deliver the outcomes promised in the feasibility studies. Case studies of installations are presented.

Jan 1, 2004

By P. Zhang

A multiyear, comprehensive study of flotation reagents used in phosphate beneficiation was conducted. The study involved the evaluation of pure fatty acid compounds, comparison of various anionic collectors and testing of iso-acids. Various C12 to C22 fatty acids were tested as Florida phosphate collectors. The saturated fatty acids were found to be very poor collectors when using the standard conditioning procedure, whereas the unsaturated C16 to C22 fatty acids showed fair to good phosphate collecting ability. The C18 fatty acids oleic, impure oleic and linoleic and the C20 eicosenoic acid were shown to be the best phosphate collectors. The best flotation results were obtained using Liqro GA tall oil and oleic acid. Four isostearic/iso oleic acid type fatty acid collectors were compared with a commercial grade oleic acid and with Liqro GA tall oil as phosphate collectors using standard laboratory conditioning and flotation procedures. The most selective collector evaluated was Century 1108, a high isostearic acid-type reagent. However, it was concluded that this excellent-performing reagent was too expensive for commercial use. Overall, the most promising reagent was probably Century MO-5. This collector is essentially an iso-oleic acid/stearic acid mixture (not isostearic acid), and it costs much less. This program laid a sound foundation for developing single collector, all anionic flotation processes.

Jan 1, 2009

By Bill Tucker, Mike Black

"PROJECT OVERVIEW Crossrail, Europe’s largest construction project, will increase London’s transportation capacity by 10% when it opens in 2018. The Crossrail scheme is a combination of surface and underground railway that stretches 118km east-west through central London from Reading, Berkshire and Heathrow airport in the west to Shenfield, Essex and Abbey Wood in the London Boroughs of Greenwich and Bexley in the east. Crossrail will serve 40 stations, ten of which are new, and bring 1.5 million people within 45 minutes commuting distance of London’s key central business districts. 21km of the Crossrail route comprises twin-tunnels beneath the heart of central London. It is the central section of the route, and the challenges that had to be overcome to construct its tunnels under the historic capital that forms the subject of this paper. The route of the Crossrail tunnels can be seen in Figure 1. These tunnels weave their way through the city’s underground landscape, linking eight new underground stations which connect to the existing London Underground network, providing interchanges with nine existing lines as well as the National Rail and Docklands Light Railway networks.Crossrail began construction of enabling works in May 2009 and launched the first of eight tunnel boring machines (TBMs) in May 2012. 42km of major tunneling work was completed in May 2015, and included 11km of sprayed concrete lined tunnels at the five mined stations (Bond Street, Tottenham Court Road, Farringdon, Liverpool Street and Whitechapel) in addition to the bored tunnel sections. The remaining three sub-surface stations at Paddington, Canary Wharf and Woolwich were constructed as large open boxes prior to the TBMs passing through. Crossrail, Ltd. is a special purpose company formed by the project’s joint sponsors, Transport for London and the Department for Transport, to manage design, construction and commissioning of the project. In 2009, Crossrail engaged Bechtel Ltd. as its delivery partner and a joint venture, Transcend (comprised of CH2M, AECOM and the Nichols Group), as its programme partner. The project is being managed by an integrated programme management team which is staffed by Crossrail and its partners. The railway, when opened, will be operated by Rail for London. With tunneling completed in accordance with the project’s master control schedule, the new railway is scheduled to commence dynamic testing in late 2017, with a phased opening of the tunneled sections and stations through Central London in 2018."

Jan 1, 2016

By Craig Hartley

? A helper stands beside a continuous miner as the operator is at the controls. The operator means to push the stop button but hits the drum rotation start button by mistake. The drum begins to turn and the bits catch the helper's clothing. He is thrown violently to the ground and suffers multiple contusions. ? A farmer's wife helplessly watches her husband drawn into the claws of farm machinery while she frantically and unsucessfully searches for the control to stop the machine. ? A mechanic on the night shift replaces plugs in the lubrication systems of all three engines of an airliner following routine maintenance. In doing so', he fails to notice that "0" ring seals have not been mounted on the plugs. A few hours later, as the fully loaded airliner is cruising high over the ocean, oil pressure on one engine drops precipitously. The pilots quickly shut down the engine and turn for home. Almost immediately, the two remaining engines lose their oil and fail.

Jan 1, 1983

By D. J. Kunz

Myanmar Ivanhoe Copper Company Ltd. (MICCL) has been operating the Sabetaung- Kyisintaung (S&K) Project producing LME Grade A Copper Cathode using the Heap Leach-SX-EW Process since 1998. The mineralization is mainly Chalcocite and the mine has a life of 20 years at the designed annual production of 25,000 tonnes of cathode copper. Design capacity was achieved within two of months of start-up. The mine is among the world’s lowest cost, Heap Leach-SX-EW operations. Information regarding plant design and operation are presented along with the challenges lying ahead and the latest developments. Daniel Kunz is President and Chief Operating Officer of Ivanhoe Mines, and a director of MICCL. He has more than 20 years’ experience in mining, construction and engineering. Prior to joining Ivanhoe Mines in 1996, Mr. Kunz was Vice President and Controller of Morrison Knudsen Corporation, a major international mining and construction company. He was also President and Chief Executive Officer of MK Gold Company, a public mining company listed on NASDAQ.

Jan 1, 2001

By Irwan S. Halim

For tunnels in horizontally bedded rock, geologic factors affect the selection and design of the initial supports, including the rock propensity toward parting along bedding and the resulting high potential for rock slabbing during excavation. To evaluate this ground behavior, numerical analyses and results with Mohr-Coulomb, Hoek-Brown, and Ubiquitous Joint constitutive models were used, using the Upper Rouge CSO tunnel in Detroit, Michigan as an example. The different rock models and other geologic considerations are shown to impact the selection of the tunnel initial support and design. This paper emphasizes the appropriate selection of an analytical model based on the site specific geology to achieve an optimum initial support design.

Jan 1, 2008

By X. Zhou

In this study, the cyclonic static microbubble flotation column (FCSMC) was investigated for fluorite beneficiation. The structure and principle of the specially designed column are described. Fluorite samples from the tungsten separation tailings of the Shizhuyuan Mine, Chenzhou, Hunan Province, P.R. China, were tested using a small-scale continuous flotation test unit, and concentrates with a fluorite grade higher than 98% were obtained. One rougher and three cleaner stages in the FCSMC achieved the same separation performance as one rougher and eight cleaners in conventional flotation cells. This greatly simplified the flotation circuit and reduced operating costs.

Jan 1, 2007

By R. Tamblyn

Vertically stirred media mills are a highly effective low-footprint solution for the ultrafine grinding of industrial minerals. This work investigates the effect of media density on flow patterns within the mill. Direct irradiation of a media particle leads to decay through positron emission, consequently forming two anti-parallel gamma rays, which allow for the real time tracking of particle position. Grinding media of the same size, but with a range of specific gravities are followed using this method, and the effect on the flow within the mill is revealed. The technique is seen to be an effective method to highlight the velocity profiles within the mill, as well as the zones where grinding is less efficient ? areas of relatively low velocity and high residence time. The changing media is seen to effect the overall flow patterns within the mill, having consequential effects on the efficiency of the grind.

Jan 1, 2009

By Niels Kofoed

Upon completion of the 6,200 m (20,340 lineal ft; lft) North Tunnel drive for the Portland East Side Combined Sewer Overflow (CSO) Tunnel project in Portland, OR, the slurry tunnel boring machine (TBM) had to be returned from the Port Center shaft at Swan Island to the Opera shaft at the main mining site for the 2,700 m (8,860 lft) South Tunnel drive. At the Port Center shaft, the main 513-t (565-st) TBM and TBM tailshield were hoisted out of the shaft in two pieces using four 200-t (220-st) strand jacks mounted on a 635-t (700-st) hydraulic boom gantry system supported by Emmert International?s custom gantry tracks designed to span the shaft. After lifting the TBM components out of the shaft, the gantry system loaded the TBM components onto two Goldhofer platform trailers, which then transported the TBM and tailshield to a barge using a roll-on/roll-off method.

Jan 1, 2011

By Siegmund Babendererde, Jan O. Babendererde

Extruded Concrete Lining combines technological and financial advantages. The tunnel lining is reliably embedded in the surrounding ground as the fluid concrete is extruded at constant pressure directly behind the TBM supporting the exposed surface. Ground deformation from the TBM passage can be compensated and the ground will be pre-stressed by the extrusion process. Developments in concrete technology permit high speed tunneling by use of a slip formwork attached to the TBM. Realised projects in Milano (Italy), Lyon (France), Frankfurt (Germany) and Akima (Japan) will be demonstrated.

Jan 1, 2001

By J. Geisler

When addressing Germany’s resource supplies, we need to distinguish between those domestically available and imported ones. Resource extraction ostensibly competes with the designation of protection areas. However, the parallel existence of wildlife and plant life, and operations in the areas used for resource extractions is continually underestimated. The European Commission has compiled guidance documents facilitating the extraction of resources from protected areas. With regard to resource productivity, the market appears to be the appropriate instrument for minimising resource consumption. Policy makers are now called upon to create a legal framework leading to a consensus accepted by society.

Jan 1, 2011

By D. H. Garcia

The mining industry responded to public concerns about use of cyanide by developing a voluntary certification to allow companies to demonstrate their commitment. The International Cyanide Code (Code) establishes standards for the manufacture, transportation and use of cyanide. Key concepts in closure planning to comply with the Code are to decommission all facilities related to cyanide operations and to provide a financial assurance mechanism for those activities. Code requirements may differ from state-specific regulations, but requirements are based on closure goals for protection of the human health and the environment. Only issues related to cyanide operations are required to be included in decommissioning demonstrations. For example, the disposal method of cyanide solution holding tanks and the cost must be included in the closure plan, but information regarding closure of roads is not required. Closure costs must be based on a third-party contractor as opposed to internal budgets. Compliance with the closure requirements of the Code allows companies to show their stockholders, lending institutions, and the public that their operations are environmentally responsible.

Jan 1, 2010

By Yang Ge, Yuzhu Pan, Mansheng Chu, Jue Tang, Cong Feng, Lihua Gao, Zhenggen Liu

The low-grade nickel laterite ore used in this study was successfully upgraded through selective reduction by industrialized rotary kilns followed by magnetic separation. The results indicated that both iron metallization extent and nickel metallization extent showed obvious linear correlation. In addition, rational roasting temperature and prolonged grinding time could enhance the overall fineness level of reduced laterite nickel ore. The moderate roasting temperature at a range of 1100–1150 °C should be suitable enough to a conversion of total nickel to metallic nickel and partly inhibited the conversion of total iron. Ultimately, the obtained ferronickel alloy with a nickel content of 7.32% and an iron content of 84.15% was prepared successfully from the lowgrade nickel laterite ore containing a nickel content of 1.92%. Nickel and iron recoveries were 96.72 and 89.08% respectively, which achieved the highly efficient recovery and utilization of iron and nickel from low-grade laterite nickel ore

By Eric Jacobs

"Building and operating tunnels has been a highstakes endeavor in terms of costs, complexity, safety and impact on contractors, owners and the public for a long time. There are many variables that need to be closely monitored and managed to construct a tunnel on-time, on-budget and safely. Once built, there are also many elements that need to be monitored and managed to operate a tunnel safely and efficiently.Fundamentally, the risks to the safe and efficient construction and operation of a tunnel are a function of the degree of harm and the likelihood of the harm occurring. From a cyber security perspective, risk assessments used to inform decision makers and support risk responses are typically based on identification of relevant threats; internal and external vulnerabilities; the impact that may occur given the potential for threats to exploit vulnerabilities and the likelihood that harm will occur. This article focuses on creating awareness of vulnerabilities associated with technology used in tunnel construction and operation and some of the challenges associated with remediation of these vulnerabilities. As we all know, technology has been evolving at an accelerating pace and infiltrating every aspect of our lives in new and often exciting ways. In the world of tunneling, sensors and systems that provide position and time have become accurate, rugged and cost-effective enough to come out of the research labs and into the equipment and systems used every day. There are many opportunities to employ connected computing devices and sensors to costeffectively capture, integrate and analyze key data with minimal latency to manage risk better, improve safety and avoid surprises."

Jun 1, 2019

By M. J. Farrell

The threat of global warming and its prominent position in public discussion and political debate requires all industry to take stock of its contribution to rising atmospheric concentration of greenhouse gases. For the primary metals industry, the first step must be to identify the pattern and range of emissions at each step in the production chain. Only then can the industry assess the economic consequences of the penalties on emissions that will be imposed by governments and regulators and devise cost-effective plans to avoid or mitigate such penalties. While some work has been done to estimate carbon dioxide (CO2) emissions using Life Cycle Inventory analysis, this approach is less useful than site-by-site emissions estimates. It is the level of specific emissions at each site that will ultimately deter-mine carbon taxation liabilities and participation in emissions trading schemes. Most mining companies have moved with the times to issue sustainability reports for their operations. But in the absence of any standardized reporting format, it is difficult to make useful comparisons between even the best-reported producers on a like-with-like basis. For this reason, Minecost.com modeled the use of fuels and energy used in mining, milling, shipping and metallurgical treatment to cover ?cradle-to-gate? emissions of greenhouse gases resulting from the production of the major base metals copper, zinc, lead and nickel. Greenhouse gas emissions ? overwhelmingly carbon dioxide ? are associated with the consumption of energy at every step in the production chain, from exploration through mining to the production of refined metal. Producers of primary metal employ diverse technologies to mine, mill, smelt and refine several different types of ore. Every orebody has its own special characteristics. In addition, most base metals are produced in concentrate that must be transported to smelters, with con-sequent emissions consequences.

Jan 1, 2009