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By Marina Carreiro-Silva, Cátia Cardoso, Bruce Shillito, Lisa Mevenkamp, Alastair Brown, Maria J. Bebianno, Juliette Ravaux, Inês Martins, Nélia C. Mestre, S. Sousa Vânia

Mineral extraction activities in the deep sea will expose the local fauna to potentially toxic compounds. However, very few data are currently available on the complex ecotoxicological risks to deep-sea fauna from the potential release of heavy metals, trace metals and Rare Earth Elements (REEs). Nonetheless, this is key information essential to support the regulation of industrial activities in the deep sea. One of the fundamental issues that the MIDAS project will address consists in exploring the concept of whether the existing toxicity test protocols and limits established in shallow-water species are applicable to deep-sea mining. We will detail the specific challenges to recommending exposure limits within the deep sea and show preliminary results of comparative toxicity tests in the shallow-water and in the deep-sea environment.

Sep 1, 2014

By Felix E. Mutschler

Alkaline rock-related precious metal deposits include: • orthomagmatic platinum group elements (PGE) ± gold (Au); • porphyry copper-silver-gold (Cu-Ag-Au, ±PGE); • epithermal Au-only, and Au-Ag-base metals; • submarine exhalative Kuroko-, Cyprus-, seamount- and Yellowjacket-type deposits; and • enigmatic deposits akin to Olympic Dam. Coeval epithermal deposits related to porphyry deposits suggest the two types represent separate immiscible fluids evolved in oxidized, CO2-rich alkaline magma chambers. Alkaline rock provinces develop above mantle hot-spots, but crustal structures control the final distribution of magmas and ore fluids. Prospecting guides for alkaline rock-related precious metal deposits include the presence of evolved alkaline rocks, pervasive K-metasomatic, redox and carbonatic alteration and low level Au (±Te, etc.) anomalies. Although alkaline igneous rocks crop out in less than 1 % of the area of the North American Cordillera and craton, alkaline rock-related ore deposits have produced nearly 13% of the total United States and Canadian lode gold production. Large (31-t or 1 million-oz) deposits are common (Fig. 1), and additional deposits and reserves are being discovered. New genetic models are evolving, making alkaline rock-related precious metal prospects attractive exploration targets.

Jan 1, 1991

By Andy Mille

The paper highlights development of tunneling methodology in the UK during the years 1990-2000 using the example of two major tunneling contracts where there solution of difficult tunneling problems during construction has benefited the industry as a whole. The paper deals with specific difficulties on two Contracts. The London Water Ring Main 80 kms (50 miles) long tunnel average internal diameter 2.54 m (9 ft4 in) and the Brighton Stormwater Tunnel 5.2 km (3.2 miles) long tunnel with an internal diameter of 6 m (19 ft 8 in). The results of human endeavour and technological innovations will demonstrate the giant strides made in tunneling methodology in the last decade of the 20th Century.

Jan 1, 2001

By W. G. Brunner

The slurry wall technique has undergone an evolution from its invention to its today’s status. In the early stages slurry walls were built with cable grab, later on with much stronger hydraulic grab and last but not least with the use of the cutter technique. The cutter allows thick walls with high verticality to extreme depths through hard soil and rock formations. With the rising demand of the construction of watertight diaphragm walls different joint systems have been developed. In addition to the rapid development of excavation systems it was necessary to improve slurry treatment and desanding plants, especially in conjunction with high performance trench cutters. Deep mixing methods can be used economically for the construction of cut-off or excavation support walls where other systems such as traditional soldier beams and lagging walls would yield unsatisfactory performance, where the installation of vibrated or driven sheet piles could cause vibration induced settlements and where concrete diaphragm walls would be time consuming and expensive. The new CSM method can largely replace the more conventional single or multiple auger methods of soil mixing or jet grouting. The cutter tool is similar to a cutter used in diaphragm walls or cut-off walls and is operated with a Kelly mounted on a drilling rig or rope suspended on a crane jib or mast of a base carrier. With this system much deeper walls can be installed and even hard soil layers can be penetrated.

Jan 1, 2007

Barrick Gold plans to have four new gold mines in production by 2006. Together, the mines would increase the company’s output by 40 percent. The projects include Veladero in Argentina, Alto Chicama in Peru, Cowal in Australia and Tulawaka in Tanzania. All of them are scheduled to begin production between the first quarter of 2005 and the first quarter of 2006. They are expected to drive Barrick Gold’s growth profile to a target of 211.5 to 217.7 t (6.8 million to 7 mil-lion oz) of gold production in 2007. The company’s projected output for 2004 is 152.4 to 155.5 t (4.9 million to 5million oz) in 2004. Overall, higher production and lower costs are expected in the early years from the new mines.

Jan 1, 2004

By John Sleavin

As part of the Link Light Rail project in Seattle, WA, work was completed at the Pine Street Stub Tunnel (PSST) in early 2007 for the Central Link project. This tunnel was excavated using cut-and-cover construction within the limits of Pine Street. The stub tunnel provides a turn back via double crossover for light rail trains running in the Downtown Transit Tunnel (DTT), as well as a connection point for the next phase of the project, the University Link (Fig. 1). Designing the new University Link tunnel connection to the existing PSST was a tricky task. The on-site geotechnical conditions, buried obstructions, geometry, requirements for construction and balancing operational considerations and neighborhood stakeholder concerns associated with the recently completed PSST combined to create a uniquely challenging assignment.

Jan 1, 2010

By T. H. Chan

As the University of Hong Kong and their advisors planned their new Centennial Campus it became clear that they would have to re-provide existing water reservoirs on an adjacent site with new salt water reservoirs located underground in two new caverns. The existing reservoirs are owned by the Water Supplies Department who provide salt water for sanitary flushing and a separate potable water supply for regular use. Although underground reservoirs had not previously been adopted locally, the planning has been completed to a tight schedule and the construction is well advanced. The need to preserve historic buildings imposed constraints, as did the requirement to minimise potential construction nuisance for the local community and environment. This paper presents the background to the project and the work carried out to develop an innovative, sustainable and environmental acceptable solution. Construction progress to date is also presented.

By P. R. Dugan

Sulfur removal from high sulfur coal has several objectives including: a) reduction of the atmospheric load that contributes to the problem of acid precipitation; b) reduction of ash, which contributes to decreased energy transfer in boilers, as well as ash disposal; and c) alleviation of the social and economic dislocations reluted to uneven geographical distribution of sulfur in coal reserves. Cost in relation to the value of refined coal will govern the development of an emerging coal refining industry. Estimation of the premium paid by power companies for coal with a low sulfur content is a good estimate of the value that will be added as the result of refining. Estimates of premiums paid in 1984 are $28.65/t ($26 per st) for reduction of total sulfur from 3’% to 1% S and greater than $28.65/t ($26 per st) for removal below 1% sulfur.

Jan 8, 1987

By Michelle Lostra, Red Blanchette, Jan Babendererde, Greg Colzani

The City of Portland’s Westside CSO Project is constructing a deep tunnel system to reduce combined sewer overflows (CSO) from entering the Willamette River. Several kilometers of microtunneled pipelines connect the existing system to the new tunnel. The alignments encountered a variety of ground conditions, including fill, manmade obstructions (wood, steel piles, debris), fine-grained to dense coarse-grained materials, cobbles and boulders, all below groundwater. A slurry MTBM convertible to varying diameters, equipped with mix shield capabilities, was selected to cope with the conditions. This paper will discuss access shaft construction,

Jan 1, 2005

By D. Bessinger, J. Nell

The electrical conductivity of rutile was optimised as a function of time, temperature and gas composition. These optimised conditions were used to treat rutile/zircon feed prep concentrate samples from a South African heavy minerals producer, prior to electrostatic separation. Enhanced separation between rutile and zircon was obtained when compared to untreated samples. Samples treated in a hydrogen atmosphere and cooled in nitrogen showed the best separation when passed through a high tension electrostatic separator using conditions of high sample temperature and high relative humidity.

Jan 1, 2005

By Kanchan Mondal, Gopi Bylapudi, Anand Bhagwat

Corrosion of steel roof support systems can cause potential premature failure of the support, thus adversely affecting the excavation stability and rock-related safety. An in-house corrosion test system was designed and developed to test full-length roof bolts for material performance based on tensile load capacity and strength under different corrosive conditions found underground. The roof bolts tested are also used to identify the possible corrosion mechanisms that influenced the bolts’ performance over time. Initially, the most commonly used bolt material in the USA, the ASTM A615 grade 60 steel roof bolts, was tested with and without stresses in a simulated underground coal mining environment for approximately 6 months, and the results are discussed. Localized corrosion forms such as crevice and pitting were mainly observed after testing. The stressed and unstressed roof bolts with and without threads that were tested in alkaline coal mine corrosive environment for 6 months passed their load-bearing capacity as per ASTM F432 test standards. From the results, it is concluded that this test protocol could be applicable to test the material performance of different roof bolt metallurgies and coatings with desired modifications to the proposed methodology for the specific underground mine environment. This paper mainly discusses the test system and protocol and shortcomings of the system and makes recommendations based on the observations and results.

By Kanchan Mondal, Gopi Bylapudi, Anand Bhagwat

Corrosion of steel roof support systems can cause potential premature failure of the support, thus adversely affecting the excavation stability and rock-related safety. An in-house corrosion test system was designed and developed to test full-length roof bolts for material performance based on tensile load capacity and strength under different corrosive conditions found underground. The roof bolts tested are also used to identify the possible corrosion mechanisms that influenced the bolts’ performance over time. Initially, the most commonly used bolt material in the USA, the ASTM A615 grade 60 steel roof bolts, was tested with and without stresses in a simulated underground coal mining environment for approximately 6 months, and the results are discussed. Localized corrosion forms such as crevice and pitting were mainly observed after testing. The stressed and unstressed roof bolts with and without threads that were tested in alkaline coal mine corrosive environment for 6 months passed their load-bearing capacity as per ASTM F432 test standards. From the results, it is concluded that this test protocol could be applicable to test the material performance of different roof bolt metallurgies and coatings with desired modifications to the proposed methodology for the specific underground mine environment. This paper mainly discusses the test system and protocol and shortcomings of the system and makes recommendations based on the observations and results.

By Axel Nitschke, Josef Arnold

Bochum’s Underground Lot 306 was characterised by a confined site and unique tunnelling methods. A highly mechanized construction concept was developed to achieve high progress rates. Bespoke backup systems for muck disposal and material supply were used. For the first time in suburban tunnelling, wet shotcrete, batched onsite, was applied. A three-storey underground car park had to be undermined with only1.5 m of overburden and had to be lifted several times by “compensation grout in.” An existing operational two-lane metro tunnel was enlarged without any major impact on train operation.

Jan 1, 2005

By Werner Burger

The last decade has witnessed a rapid development and application of slurry and EPB type tunnel boring machines. Both soft ground types are able to excavate tunnels in unstable ground conditions below the water table with positive face support. The most significant component of the excavation process is the cutterhead and tool con-figuration were the excavation and face support meets the geological challenge. The TBM downstream processes cannot take place unless the cutterhead and tools effectively do their job. This paper will review the current state of the art design for both slurry and EPB cutterheads and highlight both common as well as geological specific design features.

Jan 1, 2007

By Bhaskar B. Thapa

The proposed Caldecott fourth bore will consist of a two lane highway tunnel along California State Route 24 near the City of Oakland. The proposed design and construction sequence for the 15-m-diameter tunnel are based on the New Austrian Tunneling Method (NATM). The initial support system incorporates combinations of shotcrete, rock dowels, lattice girders, spiles, and grouted steel pipe canopies. The final lining is cast-in-place reinforced concrete. A waterproofing membrane and drainage system are placed between the initial and final linings. State Route 24 is a lifeline route, required to be open to emergency vehicles within 72 hours after a major earthquake, defined as having a return period of 1,500 years and a peak ground acceleration of 1.2 g. Although the seismic design criteria are stringent, the design of the tunnel lining system is ultimately controlled by static ground loads in the weak rock along the alignment.

Jan 1, 2008

By S. Frimpong

The cable shovel excavator is used for primary production in many surface mining operations. A major problem in shovel excavation is the variability of material diggability, resulting in varying mechanical energy input and stress loading of shovel dipper-and-tooth assembly across the working bench. This variability has a huge impact on the shovel dipper and tooth assembly in hard formations. In addition, the geometrical constraints within the working environment impose production limitations resulting in low production efficiency and high operating costs. A potential solution to the above problems is the application of an intelligent cable shovel excavation(ICSE) technology. In this paper, dynamic models of the cable shovel excavator are developed with numerical examples. These models form the basis for developing dynamic shovel simulators for an intelligent shovel excavation technology. The dynamic equations are developed using the Newton-Euler techniques. The path trajectories for efficient excavation, dynamic velocity and acceleration profiles, and dimensioned parameters for optimum feed force, torques and momentum of shovel boom-bucket assembly are modeled and used for efficient excavation. The optimum digging forces and resistances for the cable shovel excavator are modeled and used to predict optimum excavation performance.

Jan 1, 2003

By Steve Kral

More than 111,350 mining and construction industry professionals from throughout the world gathered in Las Vegas, NV, March 19-23 for ConExpo-Con/Agg 2002 and IFPE 2002. The triennial event is the Western Hemisphere’s largest equipment show for the quarrying, aggregates, construction and ready-mixed concrete industries. Despite the difficulties in the world economy, ConExpo-Con/Agg 2002 attracted more than 2,450 exhibitors from throughout the world. This was an increase from the 1,882 exhibitors that were on hand for the 1999show. And this year’s show occupied more than 180,225m2 (1.94 million sq ft) of exhibit space at the Las Vegas Convention Center. This was an increase from the160,900 m2 (1.73-million sq ft) occupied at the 1999event.

Jan 1, 2002

By Steve Kral

The mining industry has had three difficult years. Commodity prices have remained low and investor confidence in the industry has been shaken. And even though the Asian economy appears to be improving, it will be some time before this improvement will translate into better commodity price conditions for mining. In addition, increased environmental and social restrictions that have been placed on the industry in developed and developing countries have made mining a more difficult proposition. And, if that is not enough, the global mining industry has found itself in fierce competition with Internet businesses for investor capital. Despite that gloomy picture, more than 10,500 mining industry professionals from about 70 countries gathered in Toronto, Ontario March 5-10, 2000 for the Mining Millennium 2000 conference. This meeting was a joint effort between the Canadian Institute of Mining, Metallurgy and Petroleum(CIM) and the Prospectors and Developers Association of Canada (PDAC).The joint meeting also featured two trade exhibitions and more than 150speakers. PDAC’s trade show attracted about 400 exhibitors and an additional 200 in the concurrent Investors’ Exchange. CIM’s exhibition attracted about 600 equipment and service companies.

Jan 1, 2000

By Amanda Elioff

Success of the Gold Line Eastside Ex-tension rail tunnels in Los Angeles, CA has prompted the Los Angeles County Metropolitan Transportation Authority?s (Metro) planning new rail lines to include underground alternatives. The Westside Extension Transit Corridor alternatives include up to 27 km (17 miles) of subway to be constructed in soft ground. The routes will require construction in Los Angeles? ?potential methane zone,? which was not considered for subway construction until recently. Slurry face tunnel boring machines (TBM) will likely be specified.

Jan 1, 2009

By I. A. Kunasz

This paper is not intended to review and re-state general information on lithium, but rather to analyze the paradigm that has caused such a rapid rise in lithium production and the development of new lithium producing centers. Details on pegmatites, brines, concentrate and chemicals are amply covered in a number of publications ? SME?s Industrial Minerals and Rocks, Industrial Minerals, Roskill and a host of other publications. There is no question that the latest interest in lithium has been driven by the potential development of the electric car. This stimulus prompts one to recall two symposia: 1. ?Lithium Resources and Requirements be the year 2000?, organized in 1976 by the U.S.G.S. in Denver (1) and the sequel 2. ?Lithium ? Needs and Resources? at Corning, N.Y. (2).

Jan 1, 2011