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By Laura McNally

In 2006 McNally International Inc. in a Joint Venture partnership with Aecon Constructors was the successful bidder on two York Region Tunnel Projects: Bathurst Collector/Langstaff Trunk Sewers; and YDSS Interceptor Sewer 19th Avenue Project. These projects comprise a total of 13 kilometres of 2.74 meter finished diameter tunnels and are both part of the York Durham Sewer System (YDSS). Both contracts require the use of EPB tunnel boring machines with a precast concrete segmental liner. The following provides an overview the two projects.

Jan 1, 2008

By Christophe Bragard

The Los Angeles Metro Eastside Extension light rail project included a 1.5 mile underground segment, which consisted of twin 18'?10" ID tunnels, bored with two EPB-TBMs. One of the major project challenges after the completion of the bored tunnels was the excavation of six cross passages within alluvial geology below the water table and with low ground cover. Sequential excavation methods were employed and this paper details the design, ground treatment, support measures, and construction methods used to mine these cross passages beneath the congested urban streets of the City of Los Angeles.

Jan 1, 2008

By N. W. Johnson

"Two analysis tools which have been applied to problems in industrial flotation processes are the application of kinetics and detailed mineralogical or liberation data, both on a size-by-size basis. This paper describes practical examples of the application of kineticsto examination of the entrainment recovery mechanism, the retardation of valuable minerals at the commencement of flotation sections and the resolution of problems related to valuable species with reduced rate constants at the end of sections. Examples of the usefulness of size-by-size liberation data for monthly composite samples of products from a concentrator are also described.IntroductionMuch of the published industrial flotation data on the behaviour of minerals in various size fractions have been obtained from specially conducted surveys with a duration of several hours. Such data are very valuable and provide a record of the behaviour of the entire flotation plant or sections during the interval of the survey. Some examples from the literature can be cited Cameron et al. (1971), Lynch et al. (1981), Frew (1982). Less attention has been given to the value of complementary sized data derived from compositing shift or daily inventory samples over an interval of one or several weeks with repetition of the procedure at the completion of each interval. Mineralogical point count data of the size fractions of such samples and data interpretation are rare in the literature.Kinetic data on the behaviour of valuable and gangue minerals in various size fractions have been reported often for flotation banks. In the experience 0 f the writer, there has been a tendency among operating metallurgists to ascribe problems in the flotation process to rate constant values for gangue minerals which were believed to be unsatisfactorily high. Less attention has been paid to the value for the rate constant for the valuable mineral over the length of a particular bank.Examples of the types of data which were mentioned previously have been obtained from the lead-zinc concentrator at Mount Isa Mines Limited. The various types of data have been collected to evaluate their worth in order to provide relevant information for both research and operational aspects of the plant."

Jan 1, 1987

By W. W. Krech, T. E. Perkins

As fractures are propagated through rocks, energy is absorbed near the extending crack tip. Apparent surface energies for several rocks have been measured by cleavage under dynamic con-ditions. At nominal crack velocities from 0.5 to 500 in (min, measurements showed that fractures propagated in discrete jumps. Calculated surface energies and moduli were relatively insensitive to nominal rate of cleavage. in another set of experiments, rocks were cleaved under high confining stresses. The rocks were submerged in low leak-off fluids which formed a filter cake on the freshly cleaved surfaces (similar to the hydraulic lracturing process). Apparent surface energies were increased substantially as the surrounding fluid pressure was increased. Moduli in bending increased significantly upon application of the first 1,000 psi but were insensitive to stress level at greater pressures. INTRODUCTION For almost 20 years, hydraulic fracturing processes have been utilized effectively to stimulate oil and gas wells. During this period, some process improvements have resulted from studies of fracture orientation, mechanics of fracturing, areas generated, conductivities of cracks, etc. Yet many questions remain concerning the conditions and pressures needed during fracture propagation. In this paper we will report additional studies of the mechanics of fracture extension. It was shown previously3 that large rock samples could be cleaved under controlled conditions so as to measure the apparent surface energy (that amount of energy absorbed per unit area of new surface created). In this paper we consider the effects of two additional factors on surface energies, viz.: (1) effect of cleavage rate and (2) effect of confining stress level. THEORY Cleavage experiments were conducted on rock samples similar to that illustrated in Fig. 1. Blocks of rock several inches wide, 2- to 3-in. thick, and up to 3 ft in length were grooved longitudinally with shallow guide slots. A crack was initiated and allowed to extend along the web as the top of the rock specimen was pulled (or pushed) apart. Auxiliary equipment permits the measurement of (1) force applied at the top, (2) separation at the top and (3) crack length. (Further experimental details will be given in the next section.) The rock beams created by the crack are considered ton be cantilever beams. The deflection (or separation of the rock beams) at any point is calculated 4,5 by the beam Eq. 1.

Jan 1, 1967

By J. -H. Wu, S. Nishiyama, Y. Ohnishi

The behaviors and stress distributions of the inclined jointed rock masses with different dip angles obtained from DDA are compared to the results of laboratory tests. By calculating the block stress distributions, it is confirmed that DDA can reproduce the arching around the trap door when lowering the trap door. The shapes of arching change with the angles of inclined layers. In addition, the earth pressures acting on the trap door shows non-symmetrical distributions when the layers are not horizontal. The stress concentration occurs in one side of the rock masses close to the trap door. Furthermore, the surface settlements are also related to the inclined angle, and the loosening zone in rock masses can be different from Terzghi’s theory [1]. Since, simulations have good agreements with the laboratory test , it demonstrates the applicability of DDA to explain the mechanical behaviors of tunnel, such as arching phenomenon, non-symmetrical earth pressure distributions acting on the trap door, and the surface settlement profile in the jointed rock masses. Dans cet article est décrite l’étude numérique du perçage d’un tunnel dans un massif de couches rocheuses jointes inclinées. La simulation à l’aide de l’Analyse de Déformation Discontinue (DDA), en faisant varier l’angle d’inclinaison des couches de roche, nous apporte des résultats en termes de distributions de contraintes et de comportement des couches, résultats qui sont ensuite comparés avec des résultats de tests en laboratoire. Les résultats confirment le fait que la DDA est capable de reproduire le phénomène d’arcage autour de la trappe lorsque la trappe s’abaisse. Les formes d’arcage varient selon l’angle d’inclinaison des couches de roche. Par ailleurs, lorsque les couches ne sont pas horizontales, la distribution de pression agissant sur la trappe est assymmétrique. La concentration de contraintes se produit du coté proche de la trappe. De plus, les tassements de surface dépendent eux aussi de l’angle d’inclinaison. En conséquence, les résultats de simulation sont en accord avec les tests en laboratoire, ce qui prouve que la DDA permet d’expliquer des comportements mécaniques du tunnel tels que l’arcage, les distributions assymmétiques de pression du sol sur la trappe, ainsi que le profil du tassement de surface dans la masse de roches jointes. Dieser Beitrag beschreibt eine numerische Studie über Tunnel im geklüftetem Fels. Das Verhalten und die Druckverteilungen in den unterschiedlich geneigten und geklüfteten Felsenmassen wird mit Hilfe des Discontinuous Deformation Analysis Programms (DDA) simuliert, und mit Laborversuchen verglichen. Die Resultate bestätigen, dass DDA der Gewölbewirkung im „Trapdoor“ Experiment gut reproduzieren kann. Die Form des Gewölbes, ändert sich mit unterschiedlichen Neigungswinkeln der Schichten. Bei geneigten Schichten entstehen unsymmetrische Druckverteilungen. Auch die Oberflächenabsenkung ist von dem Neigungswinkel abhängig. Die gute Übereinstimmung der Simulationen mit den Laborversuchen zeigt, dass die DDA-Methode gut geeignet ist, um das mechanische Verhalten von Tunneln, wie z.B. den Effekt der Gewölbewirkung, die unsymmetrischen Druckverteilungen bei geneigten Schichten, oder die Oberflächenabsenkung in geklüfteten Felsenmassen, zu erklären.

Jan 1, 2003

By J. J. Forbes

Investigations by the Bureau of Mines and by mining-research departments of European countries have established definitely the value of rock-dusting to prevent or limit the propagation of coal-mine explosions. Its effectiveness in this connection has been demonstrated not only by research but by actual coal-mine explosions in which hundreds of lives have been saved because of its presence. In a general way this paper gives pertinent facts concerning rock dusting practices in the United States. Information has been obtained from many reliable sources, and various coal-mining companies have furnished data on cost and other details.

Jan 1, 1939

By W. J. Kroll

This report on the bibliography of zirconium has been confined to those publications and patents that appear to be useful in the commercial development of the metal, both the malleable and the nonmalleable. The methods of production have been stressed and special attention has been given to the alloys. Compounds of importance, like the oxide and chloride, for the manufacture of the metal or of the alloys have been considered. The use of the oxide in refractories anal in the glass and porcelain industries has been omitted. The present survey is critical; that is to say, an attempt has been made to evaluate the effectiveness of suggestions made in the literature. The exhaustive work of Marden and Richy, Bureau of Mines Bulletin 186, published in 1921, has been taken as a base to start from with the intention of bringing the subject up to date with material published in the last 24 years. During this time there was considerable 'advance in the preparation of the metal and Its alloys, and in the development of new uses. On the other hand, there was little progress in the methods of decomposing the ores, so that the chapter on this latter phase is necessarily short.

Jan 1, 1946

By L Semenyna, W Douglas

Gold is often present in solid solution with pyrite in the Carlin Trend. The presence of organic carbon along with gold hosted in sulfide, referred to as double refractory ore, requires that ore with high carbon-in-leach (CIL) preg-robbing potential and poor leach recovery is routed to a roaster. During roasting, the pyrite is oxidised to (ideally) form hematite (Fe2O3), and the gold that was present as solid solution in the pyrite forms colloids within the hematite. The ideal texture of the produced hematite is porous to allow for the penetration of cyanide for gold dissolution. Temperature and other conditions of roasting, as well as ore characteristics (pyrite mineral associations, arsenic) can affect the texture and the type of iron oxide formed. Many of these alternate iron oxide minerals result in incomplete leaching. Comprehensive gold deportment studies have proven that the majority of the gold losses in Barrick GoldstrikeÆs roaster leach tailings occur within the iron oxides created through the roasting process.The iron oxide phase that hosts the majority of the gold in tailings is in the form of by-product maghemite (?Fe2O3), which is highly magnetic. Barrick Goldstrike has designed a magnetic recovery circuit to capture these iron oxides, and with subsequent reprocessing, recover the lost gold. Pilot plant results and analysis using scanning electron microscope mineral liberation analyser (SEM MLA) shows that up to 30 per cent of the gold in tailings can be recovered with a three per cent overall mass pull to magnetic concentrate. This magnetic concentrate can be economically reprocessed, resulting in a three per cent improvement in roaster recovery.CITATION:Douglas, W and Semenyna, L, 2013. Magnetic recovery of gold-bearing iron oxides at Barrick GoldstrikeÆs roaster, in Proceedings World Gold 2013 , pp 79-86 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

Ecological Fuel from High-Sulfur-Content Coal

Sep 13, 2010

Anaconda Aluminum Co. began production from a new 60,000-ton-per-year potline at Sebree, KY, which brings the total capacity of the plant to 180,000 tons per year. A strike by workers at Alcan Aluminium Corp. primary aluminum smelters at Arvida, Que., Isle Maligne, Que., and Beauharnois, Que. shut down the plants and the company announced force majeure on part of its ingot supply commitments. Kaiser Aluminum and Chemical Corp. announced plans to increase its price for primary aluminum from 60.0 cents per pound to 63.0 cents per pound effective July 1.

Jan 1, 1979

By Clifford Britch

"Kaiser Resources Ltd. has completed feasibility studies resulting in approval of $277,500,000 for the construction of the Greenhills Surface Coal Mine, located 35 km north of Sparwood, B.C. The mine is designed to produce 1,800,000 tonnes per year of metallurgical coal over a 20-year period by conventional truck /shovel methods.The project is in the detailed design phase, with some preparation work being carried out on the site. The major construction activities are scheduled to commence in the spring of 1981. Mine development and pre-stripping will commence in July 1981, with first coal production scheduled for mid 1983.This paper will be a general description of the project and will include a discussion of the geology, reserves, mine planning, coal handling and processing, surface facilities and related topics.IntroductionProject DefinitionThe Greenhills Project is designed to produce, by conventional truck I shovel surface mining methods, 1,800,000 clean tonnes of metallurgical coal per year for twenty years . The production/ life constraints were chosen as being meaningful for planning and evaluation purposes after appraisal of the market potential and are not limited .by economic reserves. Substantial additional strippable reserves are available which would facilitate expansion of the proposed mine life and/ or capacity. In fact , all the facilities are designed so that they can be expanded in the future to accommodate a doubling of annual coal production, and certain portions of the coal processing facilities are being installed with an annual capacity of 3,600,000 tonnes. The mine will also produce approximately 2,400,000 clean tonnes of oxidized thermal coal, mostly in the first decade."

Jan 1, 1981

There is an alternative theory of the high grade orebodies of the Middleback Group, based on the primary nature of the high grade ores in an area of carbonate deposition, with lesser amounts of siliceous and aluminous sediments. The environment is thought to have been unstable, possibly volcanic, and to have been a subsiding basin, substantially isolated from the open sea.Jaspilites, iron bearing talc rocks and iron bearing carbonate rocks were derived from the primary sediments by metasomatic alteration after metamorphism.The metasomatic agents were carbon dioxide and water vapour which were mobilized from the primary dolomite and reacted with a metamorphically produced group of iron bearing and iron free amphiboles, forming talc and progressively releasing silica and iron oxides from the iron amphiboles.The talc rocks in turn released silica which reconstituted jaspilites into their present 200 ft thick crust or zone.The theory accounts for the present disposition of a jaspilite zone over a talc zone which in turn overlies a carbonate zone, and accounts for the down dip changes found in bores which penetrate these zones.INTRODUCTIONIron Duke (Fig. 1) lies some 34 miles south west of WhyalIa in South Australia, and is the most southerly ore body in the Middleback Ranges.The Middleback Ranges are divided into a northern range and a southern range meridionally disposed and separated by an erosion gap called Kimba Gap.The South Middleback Range contains four orebodies;Iron Duke at the southern extremity, Iron Duchess north of Iron Duke and on the same ridge, Iron Knight also on the same ridge, which has been breached by erosion between theDuchess and Knight orebodies, and north east of Iron Knight, the Iron Chieftain.Cook's Range is the eastern range of the South Middleback Range and no large orebodies are known to occur there.

Jan 1, 1963

By William D. Hissem

For those blasthole applications which require the use of holes ranging from 1” to 5.5” in diameter, the use of top hammer drills has been the equipment of choice for several generations of drillers. Pneumatic compressed air and hydraulic compressed oil systems represent the primary technologies which are available to the drilling practitioner. While both employ the same operating principals, the characteristics of performance, cost, and reliability can be markedly different between technologies and manufacturers.

Jan 1, 1998

By Richard D. Smith

The Bureau of Mines evaluated the emission control methods, including the capital investments and operating cost, necessary for further reducing lead levels in ambient air at the Glover, Herculaneum, and Buick smelter-refineries in Missouri and the East Helena, MT, smelter. The U.S. Environmental Protection Agency (EPA) has proposed more stringent lead in ambient air standards than those currently in effect. This report presents theoretically achievable lead emission reductions and estimated capital and operating costs. Lead emission inventories theoretically can be reduced from 1985 levels by 2,421 lb/d at the three Missouri operations by containing and filtering fugitive emissions within structural enclosures and baghouses. The aggregated capital and operating costs in 1986 dollars using conventional environmental and workplace technologies are estimated to be $250,014,100 and $18,507,800, respectively. Estimated total incremental cost is $0.063/lb as refined lead. Additional regulatory costs attributable to Occupational Safety and Health Administration (OSKA), U.S. Department of Labor, workplace standards are included since proposed environmental controls may otherwise degrade workplace conditions. Continuous drossing is evaluated as an alternative to conventional OSHA controls. Substituting continuous drossing for conventional work- place technology results in an estimated aggregated capital and operating costs of $258,344,800 and $15,719,600, respectively. Estimated total incremental cost is $0.062/1b as refined lead. For comparison, the average open market price of refined lead during the first quarter of 1986 was $0.184/lb.

Jan 1, 1987

By Kurt RP Petersen, Hendriena van der Walt

With the decline in fine diamond production from the Argyle mine in Australia, there is a greater emphasis on efficiently treating the finer size fractions through a DMS circuit. Although it is generally well understood that smaller diameter cyclones are more appropriate for this application, practical results do not necessarily meet this expectation. In this paper the operational performance of particular sized cyclones throughout the group was compared. Based on the results there is evidence that under certain practical operating conditions, small cyclones are not necessarily best for fine size particle treatment, particularly given the production pressures faced by all mines. However, there seems to be considerable merit in using larger sized cyclones, which tend to exhibit less performance variability, irrespective of operation conditions.

Jan 1, 2006

By Leonard Weixler, Peter Halbach, Michael Jarowinsky, Johannes Post

Germany as an industrial nation is highly dependent on the import of mineral or metal resources. Sources which have not been considered until now are the marine mineral resources (MMR), which in recent times are enjoying more and more increasing interests and which might provide in the future a considerable contribution to the supply security on metal resources not only for the industrial countries. Backed up by the German government’s "National Masterplan Maritime Technologies" (NMMT) and corresponding industrial R&D-activities, the idea and the advantages of deep-sea mining is gaining more and more interests and supporters with respect to industrial and political considerations on strategic raw material resources as well as on the development of deep-sea mining technologies. The NMMT aims to initiate growth and increase the competitiveness of the German maritime industry on international markets and covers about 10 different marine and ocean technology sectors including deep-sea mining.

Sep 1, 2014

By Mohamed A. Younis, Paul J. Headland, Paul H. Madsen, Vojtech Gall

INTRODUCTION A 100 ft long, 20 ft high and 18 ft wide NATM tunnel was excavated through grouted clean sands beneath a busy city street, including a variety of existing utility lines. The new tunnel associated with a hospital expansion will serve as a pedestrian tunnel connecting a parking structure with a new hospital facility. Tunnel construction started on December 15, 2005 when drilling for the grouting program started and was completed on May 26, 2006 when the tunnel final lining was completed. The tunnel was constructed by Kiewit Construction Company as a tunnel subcontractor to The Christman Company who is constructing the hospital facility for Spectrum Health in Grand Rapids, Michigan. URS was the project designer. GallZeidler Consultants, LLC were the contractor’s NATM consultant. PROJECT DESCRIPTION The Michigan Street Pedestrian Tunnel is a component of the Michigan Street Development located along the north side of Michigan Street NE between Coit Avenue NE and North Division Avenue in the downtown area of the Grand Rapids, Michigan. The Michigan Street Development includes a parking deck and four new towers to be constructed over the proposed parking deck. The tower planned furthest east is being developed by Spectrum Health as the Lemmen-Holton Cancer Pavillion. The purpose of the pedestrian tunnel is to connect the proposed Lemmen-Holton Cancer Pavillion with the future Spectrum building to be located on the south side of Michigan Street NE. The southern end of the tunnel was constructed with a bulkhead until the future Spectrum building is constructed at which time interconnection will be required. The tunnel site plan and profile are shown in Figure 1, Site Plan, and Figure 2, Tunnel Profile. Several challenges were faced during the design and construction of the Michigan Street Pedestrian Tunnel. These challenges included compressed design and construction schedule, maintenance of traffic and protection of old underground utilities. The tunnel was being constructed as part of the Michigan Street Development and coordination with other concurrent construction activities was required. The tunnel was constructed within a specified window of time to allow other associated construction activities to take place without compromising the overall project schedule. The design started in June 2005 and construction was completed by June 2006.

Jan 1, 2007

Using a series-model of an automotive short range radar sensor (SRR) and a recently completed experimental radar system, field tests have been performed in a surface mine. It was examined, to what extent low-cost electronically scanning radar sensors can provide useful data for assistance systems on large scale mining machines. Simple sensors are useful for anti-collision safety zones or hopper car automation. The more complex and sophisticated experimental radar system using digital beam-forming can clearly detect and map the contours of trenches and slopes. The overall promising results refer to many more potential applications for electronically scanning radar in surface and underground mining as a reliable alternative to mechanical laser scanners.

Jan 1, 2007

By W. R. Paterson, W. Morton, D. B. Cameron

The Massbal II computer simulation program has been used to develop a general framework for the building of thermochemical models of metallurgical processes. The framework allows the rapid, simple construction of complex models of process equipment for use in flowsheet design, planning and plant operation. Application of the program to model the iron-making blast furnace and a flash smelting process is described

Apr 1, 1991

By W. J. Schlitt

The Namibian Copper Joint Venture has been formed to undertake development of the Haib copper deposit, one of the largest undeveloped copper resources in Africa. The development programme includes extensive hydrometallurgical testwork that is being managed by Kvaerner Metals (formerly Davy International).Various parts of the programme have been contracted to four third-party laboratories. The testwork involves sample selection and characterization, amenability tests, and a parametric study on the leaching variables. All portions of the programme are described and the results a represented. The ores selected for testing are quartz feldspar porphyries. The amenability tests include ?mapping? studies to assess optimum leach conditions, tests at high oxidation potentials, oxidation with various bacterial strains, and heap leach modelling. The parametric programme includes such variables as ore grade, leach temperature, crush size, pH, and ferric iron content of the lixiviant. Testing was done on both whole ore and concentrate. Results show that bacterial leaching is effective and that ore grade and temperature are key variables. Crush size and pH have less impact on copper extraction. For mid-grade ore, about 0.25 per cent copper, extraction is projected to reach 50 per cent after two years when heap leaching tertiary crushed ore at 60°C and pH 1.5. The heap leach operation would fit well with the proposed roast-leach operation used to treat higher grade ores. The latter could supply the low cost heat and acid needed in the heap leach.

Jan 1, 1999