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By Wayne Green

The Regional Municipality of York, located north of the City of Toronto in Ontario, Canada, has experienced unprecedented growth during the past decade, with new home construction averaging 15,000 units per year. This rate of growth is planned to continue well into the future with a projected growth of more than 500,000 new residents by 2031, combined with a tar-get of more than 300,000 new jobs to provide a sustainable economic base for the region. It should be noted that York region has been designated as one of the key growth centers by the province of Ontario, aimed in part to meet the housing and employment needs of Canada?s growing population. York Region is a mix of urban and rural areas and is one of the most desirable areas to live in Southern Ontario. York region offers an attractive lifestyle, with its nine municipalities and the amenities created by the many rivers, streams and protected greenbelt areas that encompass more than 69 per cent of the region?s area.

Jan 1, 2010

During the last 20 years, more than 80 km (50 miles) of tunnels have been constructed in the Los Angeles, CA area. Recent projects include The East Central Interceptor Sewer (ECIS), completed in 2004. It spans more than 18 km (11 miles). The Northeast Interceptor Sewer (NEIS), completed in 2005, spans 11 km (7 miles). And the 2-km (1.3-mile) Metropolitan Transportation Authority?s Gold Line Eastside Extension (MCGLEE) was completed in 2006. All of the tunnel routes lay beneath heavily populated urban environments so minimizing ground surface settlement was critical to the success of the projects. Previous tunneling efforts in the Los Angeles area using open shield methods resulted in significant settlement that damaged roads, utilities, buildings and other structures. Earth pressure balance (EPB), or slurry machines, were specified for these projects to reduce subsidence risk. The contractors chose EPB tunnel boring machines (TBM) for the work. The closed and pressured face of the EPB TBM reduces loss of ground at the tunnel face and, when the machines are used in combination with gasketed pre-cast tunnel liners and backfill grout behind the installed segments, losses from over-cut of the excavated surface are also reduced.

Jan 1, 2008

By Thomas G. Goonan

Copper production through smelting generates large volumes of material flows. As copper contained in ore becomes copper contained in concentrate to be fed into the smelting process, it leaves behind an altered landscape, sometimes mine waste, and always mill tailings. Copper concentrate, fluxing materials, fuels, oxygen, recyclables, scrap and water are in-puts to the process. Dust (recycled),gases — containing carbon dioxide(CO2) (dissipated) and sulfur dioxide (SO2) (mostly collected, transformed and sold) and slag (discarded or sold) — are among the significant process outputs. This article reports estimates of the flows of these input/output materials for a particular set of smelters studied in some countries. They include Chile (Altonorte, Caletones, Chagres, Chuquicamata, LasVentanas and Potrerillos), Japan(Naoshima, Onahama, Saganoseki,Tamano and Toyo), the United States(Garfield — Fig. 1 — Miami and Hayden) and Europe (Glogow I, Glogow II, Huelva, Norddeutscheand Ronnskar).

Jan 1, 2005

By Erich J. Jacob

In the past 15 years the enforced improvement of the public traffic systems caused a boom in urban tunnel construction. In 1961 the City of Paris started to build the Express-Metro. Of the 47 km long double-track line crossing the city center, nearly 45 km are in operation since 1971. Still missing is here only an about 2.6 km long connecting stretch, which is under construction now. From 1963 to 1969 the 21.8 km long Victoria Line was built in London as extension of the existing network,. A little later, in the years 1965 to 1973, the City of Hamburg supplemented its subway network by the construction of a 16.8 km long line between the Boroughs of Billstedt and Stellingen. Also in 1965 the City o Munich started to build a subway system of 54 km f length. Thereof a stretch of 16.2 km could be taken into operation in 1972 shortly before the Olympic Games. These are only some of the better known projectsas examples of the activities in European cities. In nearly all cities with more than about ½ million inhabitants subsurface traffic lines were begun or supplemented. Furthermore, numerous undercuts or other subsurface structures were built. The Ij Tunnel in Amsterdam and the new Elbe Tunnel in Hamburg may be mentioned, both structures finding international attention.

Jan 1, 1976

By Rafael C. Castro, Geoffrey Hughes, Fredrick (Rick) Vincent, Philip H. Albert

Seven pairs of drop and ventilation shafts, between two and nine feet in diameter, will convey combined sewer flow to a 230-foot-deep, 26-foot diameter storage tunnel. This paper will present case histories for each site. Discussion will include functional requirements, program and site access constraints, structural design, geology, the variety of excavation and lining construction methods used, and lessons learned. Noteworthy observations include the importance of assuring competent ground sup-port at the soil-bedrock interface and of achieving tight verticality tolerance using both top-down and raise bore excavation methods.

Jan 1, 2007

By B. Burke, R. Colquhoun, K. Thomas, R. Walton, D. Fentie

The new Roasting Facility at Barrick’s Goldstrike Mine in Nevada, U.S.A. was developed to process 12,000 tons per day of refractory gold ore. The process consists of crushing, dry grinding, roasting, extensive gas purification, calcine quenching and leaching in the presence of activated carbon. The new plant is integrated into the existing Goldstrike facility, treating ore from both open pit and underground sources. The process design, procurement, construction and commissioning of the Roaster facility was performed successfully over a 3½ year period with peaks of 400 engineering personnel and 950 construction personnel supporting the project. The US$330,000,000 project was completed ahead of schedule and under budget. The commissioning was well planned and proceeded smoothly through a rapid start-up to achieve all primary goals within three months of the start of processing of ore.

Jan 1, 2001

By T. Tafi

The Ute-Ulay project area is located approximately five miles west of Lake City, in Hinsdale County, Colorado. The Ute-Ulay Mine site is approximately one mile east of the project area. The elevation of the site is 9,200 feet and is adjacent to Henson Creek (Figure 1) [ ] The Ute-Ulay Mining complex is an inactive gold, silver, and zinc mining/milling operation, that operated from the 1880?s until the 1970?s, and sporadically into the late 1990?s. The mining complex comprises several levels of underground mines, a flotation mill, and an abandoned town site. Due to the narrow, steep sided canyon, milled tailings were pumped upstream one mile in a sluice box to a wider section of the canyon, and deposited into five tailings impoundments and one berm located between the impoundments. An estimated 9,000 cubic yards (yd3) of fine grained tailings were located in the impoundments adjacent to the creek. The Ute-Ulay project area consisted of the mill tailings impoundments located upstream from the historic mine.

Jan 1, 2011

By Jonathan Taylor, Irwan Halim, Frederick (Rick) Vincent

The new underground facilities for the LINAC Coherent Light Source project at the Stanford Linear Accelerator Center in Menlo Park, CA, are constructed in very weak sedimentary rock interspersed with uncemented zones. In addition to several 21-footwide (excavated) tunnels, the NATM excavations include a large, 49-foot wide (excavated) cavern, an unprecedented size in this geology. The critical design issues include characterization of the weak rock, some shallow rock cover areas, and very stringent criteria for final invert slab movements within the tunnel. The design also incorporated severe seismic criteria, since the site is in close proximity to the San Andreas Fault.

Jan 1, 2007

By Steven C. Borell

For more than a decade, changes have occurred each year that have improved the regulatory and business climate for mining in Alaska. These changes have taken place during Republican and Democratic governorships as well as when the state House of Representatives and Senate were controlled by either party. During some years, the changes have been relatively minor. In others, including the 2003 legislative session, the changes could only be characterized as massive. These improvements have encouraged exploration. This, in turn, has resulted in some major new discoveries. But Alaska is essentially unexplored and tremendous opportunities remain.

Jan 1, 2004

By Ivan Weber

Asking the question, “What do the world’s leading corporations and cutting-edge practitioners of sustainability put forth to guide a given mine site for planning and action toward ‘sustainability’?”, this paper explores the spectrum of methodologies and mindsets in available literature, then constructs an example for the large near-closure facility at Kennecott Utah Copper. Values, opportunities and constraints spring from physical, unutilized byproducts, from critical ecosystems and wildlife populations, from location relative to those ecosystems and proximate communities, and from the political will to perform adequate feasibility investigations. Patience, determination and thoroughness are imperative. Identifying most productive and, simultaneously, most protective and restorative, practical methods to approach ‘sustainability’ has become a central mission of industry and business, worldwide. A survey of recent international initiatives finds no single approach that establishes either a readily adaptable methodology or an appropriate set of ‘attention’ points, or agenda, to guide individual mining operations at specific locations toward the elusive but essential goal of ‘sustainable’ mining. Untying this convoluted knot of contending factors requires willingness to recognize and work within ecological constraints for community long-term needs. Occasionally, the task requires the sword of Alexander the Great. Through integration that is unflinchingly honest ethically, culturally, economically, ecologically and scientifically, fully cognizant of place and community at whatever scales are of greatest significance, and integrative of both problem-response and opportunity, we may envision a mineral extraction and beneficiation future that achieves the best, most nearly sustainable, results possible. Industrial ecology (IE), with its clear emphasis on community, ecosystems, and sustainable economic stimulation, presents a sufficiently broad and adaptable discipline to facilitate planning and management toward sustainable mining. The creation of sustainable jobs encapsulates IE’s analogy to the niche survival strategies of organisms in nature. Open to common-sense recognition of faults and opportunities at appropriate scales, IE is less a discipline or prescribed methodology than a mindset, willing to be rigorously scientific when science is imperative, but also willing to exercise “art” when creativity or community engagement are needed. IE is also capable of future-looking compassion for peoples and nature. Looking beyond what has occurred to date, the case of Kennecott Utah Copper provides ample illustration of possibilities for community economic development, environmental management, and significant initiatives beneficial at regional and planetary scales, to become recognizable as deserving of the label, ‘sustainable.’ Through what this researcher terms “whole mine, whole region, whole planet” thinking, strategies become visible and subject to serious consideration, presenting a path to best possible accomplishment in mining. Constituting a maximal broadening of mining’s “traditional” scope, the integrative approach proposed here is the ‘paradigm shift’ being made by many other industries around the world. In aggregate, these steps are the only hope for avoidance of environmental, social and economic risks that threaten to curtail resource development and impair mining companies’ ‘social license to operate.’

Jan 1, 2005

By T. A. Rundle, K. Kim, W. M. McCabe, E. C. Gregory

Overcoring tests were conducted at the Near-Surface Test Facility(NSTF) to assess the suitability of five techniques (U.S. Bureau of Mines borehole deformation gauge (BDG), Commonwealth Scientific and Industrial Research Organization (CSIRO) hollow inclusion stress cell, Luleå triaxial gauge (LuH gauge), and Council for Scientific and Industrial Research (CSIR) doorstopper) for in situ stress determination in a closely jointed basalt. This effort is in support of the Basalt Waste Isolation Project, which is studying the feasibility of locating a nuclear waste repository in the basalts of the Hanford Site in southeastern Washington. This paper presents the results from the overcoring study that formed the basis for selection of two techniques to be used during the further exploration of the basalt formations at depth.

Jan 1, 1983

Colloidal interactions play a critical role in mineral processing, including grinding, physical separation (particularly flotation), dewatering, and tailings management. Despite great energy input in comminution to liberate valuables from gangues, heterocoagulation between valuables and gangues would prevent the separation of valuables from gangues. On the other hand, selective coagulation/flocculation to increase the size of desired fine particles could enhance physical separation and dewatering, while dispersion is needed for fine grinding. To control the state of colloidal dispersions by creating favorable conditions, it is of paramount importance to study colloidal interactions in a relevant system and understand underlying mechanisms. This review summarizes recent advances in developing the-state-of-the-art techniques and novel methods of measuring colloidal forces, including atomic force microscope, surface force apparatus, zeta potential distribution measurement, quartz crystal microbalance with dissipation, and our recently developed integrated dynamic force apparatus. The basic principle of each technique was introduced first, followed by a summary of critical information derived for the relevant mineral processing systems. Finally, the pros and cons of each technique were discussed to emphasize the use of complementary techniques that assist in solving fundamental problems in mineral processing.

By K. Saikiran, A. R. Nalla

Longwall management, regular shield maintenance, and evaluation of ground control problems can be performed using real-time shield monitoring program. Based on real-time shield pressure data, evaluation of intensity and interval of periodic weighting, estimation of time-dependent pressure increase and the effects of geologic anomalies can be obtained. In this study, full-face shield pressure data of over 457 m (1,500 feet) of face advancement is analyzed to evaluate shield response in the presence of surface lineaments, floor undulations, and multiple main roofs. Shield pressure increase due to web cutting is also correlated with setting pressure during periodic weighting and normal time. In addition, time-dependent pressure increase rate on Sundays and holidays is also correlated with time average pressure and the location of previous periodic weighting.

Jan 1, 2000

By Mustapha A. Raji, Alafara A. Baba, Christianah O. Adeyemi, Aishat Y. Abdulkareem, Rafiu B. Bale, Malay K. Ghosh

The increasing demand for pure aluminum and aluminum compounds of industrial quality from kaolinite ore cannot be overemphasized. Nigeria is one of the African countries endowed with abundant solid mineral resources that have not been sufficiently exploited to assist its indigenous industries. A wide array of applications of pure aluminum and its compounds are available, such as paper filling, refractories, adsorbent, catalysis, and paint additives. In this study, the upgrading of a Nigerian biotite-rich kaolinite ore by a hydrometallurgical route was investigated in oxalic acid media. During leaching studies, the effects of parameters including reaction temperature, lixiviant concentration and particle size on the extent of ore dissolution were examined. At optimal conditions (1.0 mol/L C2H2O4, 75 °C), 92.0% of the initial 10 g/L ore was reacted within 120 min. The dissolution curves from the shrinking core model were analyzed and found to conform to the assumption of surface diffusion reaction, and the calculated activation energy of 33.2 kJ/mol supported the proposed model. The unreacted product (~8.0%) analyzed by XRD was found to contain siliceous impurities and could serve as a valuable by-product for certain industries.

By Mustapha A. Raji, Alafara A. Baba, Christianah O. Adeyemi, Aishat Y. Abdulkareem, Rafiu B. Bale, Malay K. Ghosh

The increasing demand for pure aluminum and aluminum compounds of industrial quality from kaolinite ore cannot be overemphasized. Nigeria is one of the African countries endowed with abundant solid mineral resources that have not been sufficiently exploited to assist its indigenous industries. A wide array of applications of pure aluminum and its compounds are available, such as paper filling, refractories, adsorbent, catalysis, and paint additives. In this study, the upgrading of a Nigerian biotite-rich kaolinite ore by a hydrometallurgical route was investigated in oxalic acid media. During leaching studies, the effects of parameters including reaction temperature, lixiviant concentration and particle size on the extent of ore dissolution were examined. At optimal conditions (1.0 mol/L C2H2O4, 75 °C), 92.0% of the initial 10 g/L ore was reacted within 120 min. The dissolution curves from the shrinking core model were analyzed and found to conform to the assumption of surface diffusion reaction, and the calculated activation energy of 33.2 kJ/mol supported the proposed model. The unreacted product (~8.0%) analyzed by XRD was found to contain siliceous impurities and could serve as a valuable by-product for certain industries.

By John Addison

Experimental animal studies comparing asbestos and non-asbestos varieties of tremolite indicate tremolite asbestos is markedly more carcinogenic. By direct analogy, the differences in carcinogenicity between tremolite asbestos and non-asbestos prismatic tremolite should be the same for the other types of amphibole that also crystallize in the asbestos and non-asbestos habits. The earliest of the experiment animal studies, done more than 25 years ago, have design limitations by modern standards including the use of injection or surgical implantation as the route of administration rather than the more relevant route of inhalation. However, the differences in the carcinogenicity of amphibole asbestos and non-asbestos amphiboles are sufficiently large to be clearly discernable even with the study limitations. Together with later studies on these and related minerals, there is strong evidence of a much lower hazard associated with the shorter, thicker fibers of the non-asbestos amphiboles, than is found for the asbestos analogues of the same mineral. It is possible that the non-asbestos amphiboles are no more hazardous than other silicate minerals widely considered nuisance dusts. © 2007 Elsevier Inc. All rights reserved. Keywords: Amphibole; Asbestos; Tremolite; Carcinogenic

Jan 1, 2007

By L. Kulik, J. den Drijver

Rhenish lignite will continue to play an indispensible role in the energy mix of the German Federal Republic for a long time to come. The use of lignite for electricity generation, upgrading and, if necessary, as a raw material is geared to the long term. The holistic management of opencast mines underpinned by approval law in the long term and a stronger focus on man, the environment and nature contribute to the acceptance of the mines by the local population. The same is true of state-of-the-art lignite uses: as regards their operational flexibility, lignite-fired power plants are ideal partners for the expansion of renewables. It is along these lines that RWE is continuing its power plant renewal programme as planned. With a view to that which will be conceivable the day after tomorrow, RWE is researching future technologies today in order to meet objectives such as security of supply, profitability and environmental compatibility to the same extent in the long term. Another important contribution to acceptance is public transparency and communications as means to support approval procedures and the implementation of measures in all areas related to lignite mining and utilization.

Jan 1, 2011

By James J. Kabat, James A. McDonald

Impregilo/SA Healy JV recently completed this Project using the first slurry shield TBM’s in the United States. The Project used two TBM’s to mine 18,000 feet in sands, gravels, and silty alluvial materials under the Willamette River and downtown Portland, Oregon. This paper discusses alignment and geological conditions, equipment selection and plant setup, and tunnel excavation means and methods, parameters, and results. Extensive hyperbaric operations were required and will also be discussed.

Jan 1, 2007

By Dennis Ofiara, Michael Lewis

An experimental 1.75 meter Shaft Boring Machine was designed and manufactured by The Robbins Company. The drill was used by contractor Drillcon Raise AB to drill test shafts at an SKB underground test facility. SKB is the Swedish authority responsible for safe management of nuclear waste materials. This “SBM1.8” Shaft Boring Machine was used to drill shallow test shafts ingranitic rock at SKB’s Aspo underground laboratory. The drill used a unique vacuum mucking system. The bored shafts were held to very strict tolerances for bore diameter, straightness, and verticality. This drill was launched and operated from a mobile launcher. Headroom and working space were limited. The SBM1.8 drill produced acceptable test holes. SKB will carry out several studies to determine the suitability of this geology, and of this technique, for safe nuclear disposal. In addition to future use at SKB, many applications are foreseen, particularly in the civil construction industry.

Jan 1, 2005

By David Chapman, Glen Frank

Due to the transport mechanics of the depositional environment, glacial soils display a very wide range of grain sizes and behavior. Several nonstandard drilling, sampling, and analytical techniques are therefore required to characterize the subsurface. The paper summarizes the geotechnical investigation for the design of a large project in glacial geology, which will include both large and small diameter pressure balance tunneling. The paper focuses on the challenges presented by the glacial environment and the techniques required to identify and characterize it for design and contract document preparation.

Jan 1, 2001