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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 D. M. Abbott, H. J. Sandri

The geoscience matrix method has proven useful for valuing metallic mineral properties lacking delineated mineral resources or reserves. However, the method explicitly excludes commodity markets from the factors considered; marketability is assumed. When valuing industrial mineral properties, marketability cannot be assumed, it must considered. Market considerations may also significantly affect the standard weightings of geoscience matrix parameters such as the proximity to known deposits. In some cases, such proximity is desirable but in many cases it is undesirable. Application of the geoscience matrix method to industrial mineral properties therefore requires thoughtful, market-related adjustments to the basic geoscience matrix methodology.

Jan 1, 2000

By H. Polat, Q. Hu, S. Chander

The collection efficiency of dust particles was determined in a laboratory dust chamber equipped with a water spray. Measurements were made in the presence of selected nonionic, cationic and anionic surfactants. For the nonionic and the anionic reagents, efficiency was maximum in a narrow range of concentration. The surfactant concentration corresponding to high collection efficiency was usually much below the commonly used concentration of l%, however. In comparison, much higher collection efficiency was observed for a cationic surfactant at extremely low concentrations. For delineating the mechanism of capture of dust particles, surface tension and contact angle results were used to obtain a correlation between the work of adhesion and the efficiency of collection. Such a correlation was reasonable for the nonionic surfactants but not for charged surfactants. In the latter case, electrostatic interactions between charged droplets and particles were more important, especially for the cationic reagent.

Jan 1, 1992

By K. J. Stanaway

Major world ilmenite and rutile accumulations reveal similar regional geology and Proterozoic age deeper crustal source rocks. During crustal collision titanium crystallizes as ilmenite and rutile at buried sites of high pressure and temperature rock metamorphism. Hydrothermal activity can convert titanium minerals to rutile, but titanium migration and enrichment seem only local. Many melts crystallize rocks with iron-titanium oxides in solid solution, but titanium enrichment at economic scale takes place in basic intrusive melts often associated with anorthosites and charnokite. Sedimentary placer enrichments have formed since the Proterozoic with water-resistant ilmenite, and rutile segregating by gravity from quartz sands deposited from flowing water. Placers have residual, alluvial, strand and shallow marine variants. Time, organic acids, and sand permeability play lead roles in the leaching of iron from ilmenite during weathering and diagenesis.

Jan 1, 2005

By D. L. Ogonowski, J. O. Marsden

The Candelaria copper-gold mine is located approximately 25 km south and east of Copiapo in Region III, Chile. The original concentrator was designed to treat 28,000 t/d (30,800 stpd) of chalcopyrite-bearing ore through a circuit consisting of a single 11.0 m(36 ft) diameter SAG mill, two ball mills, conventional rougher and scavenger flotation, column cell cleaner flotation, and ceramic disc filtration. The plant was commissioned in August 1994 and quickly reached design capacity and expected levels of metallurgical performance. In May 1996, a decision was made to double the capacity of the concentrator by the addition of a second line of equipment. The expanded facilities were commissioned in October 1997, less than 18 months after the decision to proceed, and well within the budget. The original concentrator facilities were replicated or duplicated as much as possible, however, a number of important equipment changes were made to take advantage of industry developments since the original concentrator was designed. These included the use of Eimco 120 m3 (4,200 ft3) cells for rougher and scavenger flotation and the installation of a Svedala VTM-800Vertimill for regrinding. This paper describes the rationale behind these changes and explores the reasons for the success of the project.

Jan 1, 1999

By Richard R. Klimpel

INTRODUCTION Previous papers by this author have discussed some of the difficulties involved with optimizing the performance of industrial flotation circuits, e.g. Klimpel (1988, 1989). The two major problems seem to be: 1) the inherent "systems" nature of the froth flotation process which leads to a great deal of self-compensation among the various operating options available and 2) the inherent variations in mineralogy, water chemistry, etc. that always seem to be present in industrial operations. In particular, the influence of reagent dosage has been emphasized in the above referenced work including an industrial system interaction denoted as the R/K trade-off, Klimpel (1984, 1987). Using a simple two parameter model for fitting time - recovery data, Klimpel (1980): [ ] where r is cumulative recovery at time t or at the t th cell, R is the long-term equilibrium recovery and K is the first-order rate of mass removal from the cell (time ), the definition of the R/K trade-off with increasing reagent dosage can be given as follows: at low dosages both R and K increase, at intermediate dosages R continues to increase but K starts to level out, and at high dosages, R may flatten out or still continue to increase but K starts to decrease, sometimes rather quickly. An illustration of this effect in a batch laboratory flotation cell is given in Figure 1. The purpose of this paper is to give a detailed plant illustration of this R/K trade-off phenomena with changing collector dosage which shows just how highly interactive the grindinglflotation system in sulfide mineral processing really is. This is one of about 20 plant level case studies that are being presented and evaluated in an upcoming book, Klimpel (1990). The particular study given here was completed in late 1979 on a copper ore of head grade 0.93% Cu. The frother being used was Dowfroth* 250 at a constant dosage of 0.15 g for each ton of solids feed to the rougher bank and the slurry pH was 10.2. The motivation of the study was to better understand the relationship of changes in feed rate (hence in particle size and state of liberation) with variations in collector dosage (potassium amyl xanthate). The major concern was to determine how much extra economic benefit could be gained by better utilizing the existing grinding mills and rougher bank consisting of eight identical cells. The remainder of the flotation circuit was also studied, including regrinding of rougher tails, but did not prove as critical as the rougher bank operation itself. It appeared from an overall economic viewpoint, the battle was being won or lost in the manner in which the rougher bank was being operated. This was not to minimize the roles of the scavenging and cleaning circuits but those portions of this particular circuit could be rather obviously operated to achieve maximum benefit given the specific output of the rougher bank. A special attempt was made to maintain constant ore type throughout the entire test program. Eight specific test conditions were evaluated including three different feed rates (and hence three different size distributions) to flotation. Tables 1 and 2 summarize the eight test conditions and overall recovery results at the end of the rougher bank for each test. A single test consisted of at least three consecutive eight-hour shifts operating at steady-state with composite cell lip samples taken over the final eight-hour shift. "Trademark of The Dow Chemical Company

Jan 1, 1990

By Ian Hooper, Alan Winter, Stefan Sadokierski, Craig Covil

The existing Tappan Zee Bridge was built in the late 1950s and has been working over its design traffic load for some time now. A new project, which is being jointly sponsored by the New York State Thruway Authority and Metro-North Rail Road, is looking at new alternatives to provide new road and rail crossings of the Hudson River. These include 2 to 5 mile and potentially longer tunnel crossing options that include hardrock TBM and EPBM opportunities. The paper describes the project needs and tunnel concept design work done on some of the alternatives. It also relates to the current EIS process for the project and talks about a possible double-stacked tunnel option. It also talks about the geology and environmental constraints relating to tunneling and provides and introduction to the tunnel ventilation work necessary for tunnel crossing of this magnitude. It does not report on the bridge engineering options being evaluated.

Jan 1, 2005

Sustainable development is at odds with reality in the minerals industry. Increasing world population and aspirations are leading to increased energy and mineral consumption. Non-renewable fossil fuels are being exploited at a much faster rate than they are being discovered. Mineral reserves are diminishing and of lower grade. Despite recycling, many of the economic reserves of the rarer metals on which technological society has come to depend are being depleted, and many of the bulk metals are being exploited at ever increasing rates. And yet, mining continues, with a long-term downtrend in commodity prices, matched by more efficient mining and processing. Will society turn to a low carbon economy before fossil fuels are depleted? Will prices come to better reflect the full cost of mineral production? Will technology save us, or is it at the root of the problem? The key drivers continue to be an ever increasing aspirational population and the law of supply and demand, rather than sustainability considerations. The paper illustrates this with examples of worldwide and Australian data.

Jan 1, 2011

By G. Karahalios

Industrial minerals have always enjoyed an important share in the technological growth of any country in the world. Today, extraction and trading of industrial minerals has expanded, but is also subject to stricter environmental guidelines. This paper presents the current status as well as the growth potential in the exploitation of industrial minerals in the countries of the south eastern European region, i.e. Albania, Bosnia-Herzegovina, Bulgaria, Croatia, F.Y.R.O.M., Greece, Italy, Serbia and Montenegro, Slovenia and Turkey. More specifically, annual production figures per country are presented for1992-1998. These figures are compared to each other and, where applicable, to world production figures. Trading of industrial minerals from these countries to Europe and the world and its effect to the local economies is also evaluated were such data is available.

Jan 1, 2000

By Albert Adu-Acheampong

Fairmount Mineral's Maiden Rock underground sand mine historically delivered air to ventilate diesel-powered equipment at its working faces through high-resistance, 381-mm- (15-in.-) diameter PVC distribution lines. In support of plans for expanded production, three new, low-resistance ventilation design alternatives were analyzed. The study determined that adequate ventilation for expanded production was possible with various commercially available, high-volume/ low-pressure fans combined with a systematic layout of control structures. The recommended redesign was implemented in 2001, resulting in a significant increase in flow volumes and a noticeable improvement in the mine environment.

Jan 1, 2008

By J. Warmbrodt, D. Apel, D. Nutakor, L. Grayson, M. Hilgers

MinerSIM is an augmented reality system with integrated hypermedia that is suitable for training underground miners in the basics of using a jackleg drill to install rock bolts. While statistical evidence shows that rock bolting with such a drill has an inherent level of risk, it is conjectured that this can be mediated with adequate safety training outside of the actual mine environment using a variety of educational media including interactive three-dimensional images, games, animations, and videos to describe the mechanics of rock bolting and its principles. Ultimately, trainees will install rock bolts in an immersive environment mixed with real and virtual images generated via a gaming graphics engine. This paper will discuss considerations, implementation issues, and evaluation methodologies of the MinerSIM system.

Jan 1, 2007

By C. Sun

The Leeville underground mine has been in operation since 2006 and currently produces 3,200 tons of ore per day with an average gold grade of 0.4 opt. The mine has a large horizontal extent of 2,500 feet by 500 feet and a vertical extent of 20 to 200 feet. High density of joints occurs within the host rock. Based on Rock Mass Rating and field observation, the Leeville ground conditions are characterized as poor to very poor. As such, heavy ground support is required for the mining operation in Leeville. Ore zones with a height in excess of 10 m (35 feet) are considered for longhole stoping. A typical stope measures 6.0 m (20 feet) wide, 30 to 55 m (100 to 180 feet, depending on the ground conditions) long and 10 to 30 m (35 to 100 feet, depending the thickness of ore body) high, yielding 10,000 to 20,000 tons when completed. Narrow ore zones, less than 10 m (35 feet), are mined using cut and fill. These drifts are 4.6 m (15 feet) wide by 4.6 m (15 feet) high. Based on the afore-mentioned poor ground condition, the establishment of a ground control monitoring system is key to operating both safely and successfully. The ground control monitoring system is composed of comprehensive instrument design and installation. Instruments include Multi-Point Borehole eXtensometers (MPBX) and Stretch Measurement to Assess Reinforcement Tension (SMART) cables. The monitoring system covers the mining zones and infrastructure openings. After about two year?s applications and measurements, useful data has been and continues to be collected to use in future stope and infrastructure structure design. The system provides the information making engineer and operation teams to do their job more confident and efficiency. Keywords: Ground control, Monitoring system, Long hole stope, Instrumentation.

Jan 1, 2009

By David R. Klug, Chris Gause, Troy L. Page

The Inter-Island Tunnel is one of two undersea tunnels which are part of the Boston Harbor Clean-Up Program. The tunnel is 7.7 km (25,160 ft) long, bored to a 4.3 m (14 ft) diameter in the Cambridge Argillite Formation and was finished to a 3.5 m (11.5 ft) diameter final concrete lining. The owner is the Massachusetts Water Resources Authority (MWRA) who is a regional authority responsible for overall design and construction. The tunnel's primary purpose is the transport of untreated effluent from Nut Island facility in Quincy, MA to the new treatment plant at Deer Island. Two sludge lines are installed for the transport of sludge from Deer Island to Nut Island. During construction the contractor encountered fault zones, fractured strata, and soft ground tunnel sections which liberated more ground water than was originally anticipated by the project designer. Ground water was controlled during mining and the placing of the final lining. The final lining of cast-in-place concrete had to be backfill grouted to cut off water inflows and provide contact for equal tunnel loading which is critical in long-term design. This paper deals with an engineered backfill grouting system which was the first of its type to be used in North America. It discusses the geological conditions encountered, the design criteria used in the evaluation process, and an indepth review of the various system components. It demonstrates how contractors can use knowledgeable and professional industry suppliers to solve difficult construction problems.

Jan 1, 1999

By M. Javier

Mining, waste is growing problem both physical accumulation and increasing toxic uncertainties it presents in the long run. Its value ?zero? is strictly calculated by economy. This mining model begs the question: What is the value of waste & what does it represent to the mining industry? Waste is widely accepted as a ?by product? generated as a consequences of the mining process. The abundant waste accumulation affects society, as receptor, in many ways and the waste piles of materials has no use and no destiny. In reality, this waste is monument of imperfection of the extractive industries worldwide. Our planet is finite and has strict limitations, which mining has traditionally ignored. It is time to design a new system, in which clearly, waste design must be integrated in whole mining process; it has no room to postpone. This paper presents a concept in waste design by which toxic mining waste not only can be rendered inert but also act as nutrient to help balance the ecosystems. This concept calls for extractive industries to pursue EQUILIBRIUM with nature (Geomimic). Also, this concept offers countless gains and opportunities fro the industry and by converting liabilities into assets; mining engineers become the managers and stewards of nature. Also, waste design offers new solutions for proper and sustainable waste management of the mining industry.

Jan 1, 2011

By K. Hopperstead

Ventilation planning in trackless metal mining is often taken for granted. This paper highlights the trials of planning and executing the ventilation design for Bog Zone at the Lisheen Mine. Ventilation planning for Bog Zone started at the feasibility study stage in 2003; subsequent design changes continued until 2006. In August 2006, the development of the Bog Zone ore body was accelerated through the use of contractors; in addition, the Lisheen equipment fleet was revised based on a larger load and haul fleet. As a result, the circuit was reviewed in terms of changes in design conditions and best practices. This review resulted in a 40% increase of total airflow required to mine Bog Zone. Resources utilized to design the circuit include: external review, computer modeling, and in-house Lisheen planning and operational staff review. The final ventilation design configuration was adopted in 2007, after modeling and evaluating 30 different scenarios, resulting in a better distribution of airflow, optimized secondary escape way, reduced contaminants, and a total power reduction. The value of investment in computer modeling of primary ventilation circuit and planning for staged implementation should never be underestimated.

Jan 1, 2009

By D. M. Avant, S. M. Pickering

A variety of grades of very white muscovite mica are now being produced from sedimentary sands and clays in Central Georgia. The mica is naturally concentrated near the base of the lens-shaped kaolin deposits and also disseminated in associated quartz sands. The same weathering and bacterial alteration processes which have transformed the kaolins from dark organic muds to white pigment-grade industrial clays have also removed discoloring iron from the micas and developed unusually white muscovite. Further, chemical alteration has removed some potassium from the muscovite atomic structure, resulting in an easily delaminated mica which can be cleaved to unusually fine, high bulking, high aspect ratio products. The peculiar alteration history of these sedimentary micas enables production of some of the whitest, finest particle size, and thinnest aspect ratio muscovite mica products on the world market today. Raw mica feed is obtained from kaolin and sand processing by-products, and also from beneath the useful base of abandoned kaolin mines. The processed ultrafine and filler grade muscovite mica products are used for paint, plastics, cosmetics, mold release, thermal and electrical insulation, epoxy, and dry wall joint cement markets.

Jan 1, 2002

By K. R. Griffin

Atmospheric conditions underground are constantly changing and from a safety perspective, it is critical to identify when conditions are trending abnormally. Atmospheric monitoring in underground coal mines allows mine operators to analyze atmospheric conditions underground in real-time. Real-time monitoring can then be used to identify whether atmospheric conditions underground have become problematic. The implementation of a risk assessment and management process allows operators to then use a risk-informed decision making to identify comprehensive site specific ventilation parameters. Establishing risk-informed ventilation parameters and tracking conditions relative to these parameters, management can modify ventilation plans as mine conditions develop to manage evolving risks. Ventilation risk assessment and management allows developing atmospheric monitoring technologies to be fully utilized in order to increase safety standards in the United States. This paper reviews general risk assessment approaches, state of the art ventilation based risk assessment, and the risk assessment and management application within the United States regulatory framework.

Feb 27, 2013

By William R. Yernberg

In October 1999, Liebherr-America, Liebherr Construction and Liebherr Mining Equipment held anopen house at its Newport News, VA, plant. The open house was held to celebrate the company’s50th anniversary and to demonstrate the new TI 272mining truck. Attending the open house members of the media, vendors and company representatives from all over the world. In his introductory comments, company president Peter Eller announced Liebherr’s dedication to expanding its presence in North America. Liebherr now has 30 dealers across the United States. As part of the open house, a brief history of Liebherr was presented, beginning with its creation in1949. Liebherr engineering and sales representatives were available to answer questions.

Jan 1, 2000

By Edward Skolnik

The concept of using fluid dense media to separate heavy ore constituents from the lighter gangue dates back to 1858, when it was patented by Sir Henry Bessemer. Its use in coal did not begin until after 1917, however, when Chance invented a process (which bears his name) in which lighter coal floats in a suspension of fine sand in water while heavier refuse sinks. Conklin used fine magnetite in suspension as a medium for floating anthracite in 1922, DuPont designed a plant employing organic liquids in 1936, and Belknap used a solution of calcium chloride (which Bessemer had suggested, among other media) in 1937. Separation of magnetic media by magnetic separators from the suspensions in which they were carried was introduced in a Butler Brothers ore concentrator pilot plant in 1937. The media first used were crushed steel and various grades of ferrosilicon. Since 1940, when American Cyanamid used magnetic separators to recover and clean magnetite in a coal washing circuit, virtually all heavy medium circuits have been of that type. As long as static baths are employed, as they are in the processes above, coal smaller than 9.5 mm or 6.4 mm cannot be cleaned economically in heavy medium. The settling velocities of the fine material are very low, and consequently the time required to separate the lighter coal from the heavier refuse becomes excessive. In addition, stray currents in the vessel and the upward velocities induced to keep media solids in suspension affect the finer solids to the degree that physical size becomes a more important factor than specific gravity.

Jan 8, 1980

By A. B. Cecala

An evaluation was recently performed on a district recirculation system at a trona mine in Granger, Wyoming. A 1.52m (5 ft) diameter, 37.3kw (50 hp) vane axial fan was installed in a crosscut between the intake and return airways and recirculated approximately 31.4 m'/sec (66,578 ft'/min) of air back into the intake. This amounted to a recirculation factor of approximately 20 pct of the return air. This air was part of the primary ventilation to three different continuous miner sections at operating distances of between 6l0m (2,000 ft) and 1,829m (6,000 ft) from the recirculation fan. The mine environment was constantly monitored for respirable dust, methane, and carbon monoxide in the operating sections and in the main intake and return entries. In addition, air samples were taken with and without the recirculation system during the evaluation and analyzed using gas chromatography. The results of this study showed only small increases in dust, while all other mine contaminants remained at such low levels that it was impossible to determine any relative changes from the recirculation system. Because of this, a brief SF. tracer gas analysis study was subsequently performed to more precisely determine an increase in a mine contaminant with the recirculation system.

Jan 1, 1991