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By Joseph M. McCann

The Brightwater regional wastewater treatment facility, under construction in King County, WA, includes an extensive conveyance system that will feature deep, soft-ground tunnels and shafts. Excavation of the Ballinger Way Receiving Portal to 65.8 m (216 ft) below grade through challenging geology was accomplished by means of artificial ground freezing. This paper discusses freeze design development, system installation and monitoring, and the contractual and construction challenges that were overcome, including work sequencing and excavation means and methods, together with lessons learned.

By Malcolm Ross

Fibrous minerals are common in nature but asbestiform minerals are rare. The unique mineralogical characteristic common to all the asbestos minerals is their morphologic form (or habit of crystallization) as polyfilamentous fiber bundles. The individual fibrils within the bundles have a tendency to be very long with a narrow range of diameters and grow with their long fiber axis in parallel orientation to the bundle length. The asbestiform habit imparts to the asbestos minerals sufficient flexibility and tensile strength so that most can be woven into cloth. In the past application has focused on their ability to insulate against the transfer of heat. However, these minerals possess other properties which make them useful in many industrial applications. © 2007 Elsevier Inc. All rights reserved. Keywords: Asbestos; Asbestiform; Fibrous

Jan 1, 2007

By Neil F. Archer

Due to the increased chance of violations and shutdowns by the U.S Occupational Safety and Health Administration(OSHA) and the U.S. Environmental Protection Agency (EPA), a company can save itself problems by taking control of the dust caused by conveying material. A complete dust-control policy can keep these emissions confined, sealed and suppressed, protecting the environment from fugitive, airborne dust. Material handling and processing, storage and traffic are the major dust producing sources. All industries that convey dry, light material need a dust control system.

Jan 1, 2003

By P. Bester, G. J. van der Linde

Foskor operates a mine in the Northern Province of the Republic of South Africa exploiting the igneous complex at Phalaborwa. It produces about 3 million tons of phosphate concentrate per year by means of froth flotation from 26million tons of ore of which 16 million is mined and milled onsite. The remaining 10 million tons originate at the Palabora Mining Company and is pumped as a slurry to Foskor. Two types of ore are mined and milled namely Foskorite and Pyroxenite. (The main mineral content of this ore is Apatite, Phlogopite and Diopside.) After three stages of crushing the ore is milled using 24 rod mills and 5 verti mills. The apatite is then recovered using four stages of froth flotation. The stocks of Foskorite ore are rapidly being depleted and the PMC tailings will also fall away by the year 2002 so that the whole mining operation will then be centred around the Pyroxenite ore. This will lead to substantial increases inproduction costs. The recoveries achieved in the flotation plant are largely dependent on the successful operation of the comminution section. Parts of this plant are now 35 years old and the advantages of re-engineering, new technology and automation can only be applied to a limited extent in an effort to reduce costs. It was then decided to investigate alternative milling methods, both wet and dry.

Jan 1, 1999

By John Corcoran

INTRODUCTION Content of this Report The 1300m long twin-bore 8.1m diameter Airside Road Tunnels (ART) were excavated beneath the busy taxiways and stands of Heathrow Airport between 2002and 2003. The tunnels were fully completed and handed over to the client for use early in 2005. This paper will describe the purpose of the tunnels, and the measures put in place to minimize the impact of construction on the daily activities involved in running an international airport. Terminal 5 Construction Heathrow Airport is the busiest international airport in the World, with a current capacity of circa 67 million passengers per year, based on existing infrastructure of4 passenger terminals, 1 cargo terminal, 2 runways and 170 aircraft stands. Terminal 5(T5) is being built to increase Heathrow’s passenger capacity by providing the following: 12 additional aircraft stands through redevelopment of the south apron area, in the autumn of 2004 A main terminal building (T5A) and a first satellite (T5B), and 43 additional stands by the spring of 2008, most of which will be able to receive the new generation large aircraft (Airbus A380) A second optional satellite (T5C) by year 2010 A third optional satellite (T5D) by year 2015 The total value of the project is approximately 4.2 billion pounds for the main phase of the works spanning from 2000 to 2007. Purpose of the Airside Road Tunnel The ART has been constructed to support the internal road traffic of the airport between terminals, aircraft stands, runways and taxiways, for passenger buses, service and technical vehicles. The majority of the traffic will be buses transporting passengers between the terminals and their aircraft.

Jan 1, 2005

Amid some of the worst economic conditions that the mining industry has been faced with in more than a decade, the mood among the large crowd at the 114th Annual Northwest Mining Association?s annual meeting was surprisingly upbeat. More than 2,200 attendees showed up at John Asuaga?s Golden Nugget Casino in Reno, NV for the conference held Dec. 1-5. And more than 200 companies exhibited in 240 spaces, including SME and the Minerals Information Institute. The number of attendees and exhibitors were the most for the conference in more than 10 years. The conference was held in Reno/Sparks for just the second time in its illustrious history but began under the cloud of global financial turmoil. Prior to, and during the conference, the industry news headlines were grim, to say the least. An alarming number of mine plans and expansions had been put on hold; hundreds of miners across the United States had been or were in the process of being laid off; commodity prices were falling and some of the biggest mergers in the industry fell through while miners around the world put the brakes on to take a wait-and-see approach. It was a painful time for many, but the downsizing actions taken by many mining companies was exactly what needed to happen, according to Industry Outlook Luncheon featured speaker Frederick Sturm. He is the executive vice president and chief investment strategist and member of Mackenzie?s Investment team. He has earned a reputation as one of Canada?s leading investors in natural-based companies and he also manages the Ivy Global Natural Resource Fund in the United States Sturm said that the mining industry has fallen hard and that he expects it to bounce back quickly, before falling hard again. In these tough times, he said, the companies that have pulled back on production early are doing the right thing in the long run.

Jan 1, 2009

By K. Zeidler, T. Schwind

The Fort Canning Tunnel, Singapore, is an approximately 50 feet (15m) wide vehicular tunnel under shallow ground cover that has been constructed according to the principles of the NATM. Its shallow location in soft ground combined with a high groundwater elevation in close vicinity of historically important features called for special design considerations combined with a rigorous monitoring scheme. Surface, sub-surface and in-tunnel instrumentation was installed to monitor the performance of the ground and tunnel support during construction. Comparison of actual reading data with the results from the computer modeling carried out during the design phase is provided in this paper.

Jan 1, 2007

By Remo Grandori

The Umiray Angat 13,2 km long tunnel in Philippines have been bored through extremely variable and difficult ground conditions including a number of special events. In particular the following adverse conditions were found: faults in decomposed ground, high temperature rocks, extremely rapid and important convergence phenomena, water inflows up to 800 litres per second. The special El Nino climatic conditions caused a long dry season and lower the level of the lake that was granting the access by barge to the site under the minimum navigable level. Many equipment have had therefore to be transported to site by a 10 ton capacity helicopter, after having been partially dismounted. For the same reason most of the tunnel drive have been bored servicing the site by 1 ton capacity helicopters to transport materials, spares and personnel. In order to overcome the above geological and logistic problems several innovation were introduced and tested in this project. Despite all that difficulties the 13,2 km of tunnel were bored in about 24 months, with a global average of 500 m/month.

Jan 1, 2001

By F. M. McEvoy, E. J. Steadman, R. Murfin

In England, the provision of aggregate is determined by the historical relationship between construction and aggregate consumption. This approach does not necessarily lead to sustainable decision-making and can be seen as being driven by political expediency, rather than reasonable environmental consideration. The introduction of the statutory requirement for Strategic Environmental Assessment (SEA) in the UK has provided the opportunity to examine this issue on a more rational basis. This paper provides a practical application of a SEA based approach, to the provision of aggregates at a regional level. The process, underpinned by relevant information on resources and environmental assets, suggests that alternative supply scenarios for aggregate provision are tested in a transparent, consistent manner with increased genuine stakeholder consultation. It supports a move away from "predict and provide" approaches to one where aggregates are sourced with the best balance of environmental costs and benefits.

Jan 1, 2005

By T. Wang

A new generated NaNO3 ? NaNO2 ? KNO3 ternary thermal energy storage system which has low melting point as 124°C and high specific heat capacity was studied for the short and long?term thermal stability by using the Thermogravimetric Analyzer (TGA). Based on the actual working condition of molten salt in solar two, the simulated cyclic thermal stability measurement was also conducted. The ternary system demonstrates excellent short ? term thermal stability and thermal reliability after cyclic heating and cooling processes. However, in the long ? term as well as the simulated cyclic stability measurement, large amount of weight loss was observed. Moreover, the stepwise long ? term isothermal study reveals that below 440°C the weight change is minimal and this temperature is viewed as the upper limit temperature of thermal stability for this ternary system. To determine the lost phases at high temperature above the upper thermal stability limit, techniques such as XRD and SEM are used to compare the condition of the salt mixture before and after the long ? term thermal stability study. On the basis of the comparison, it can be concluded that the major weight loss was due to the decomposition of sodium nitrite.

Jan 1, 2012

By K. W. Lee, C. Pound, J. Carmody, L. Petersen, C. Nelson, J. G. Cai

The feasibility of developing the Underground Science City below the Kent Ridge Park has been investigated. The primary aim of the study has been to explore the possibility of creating underground space to house a new community of research laboratories and offices. The investigation represents the first such study undertaken in Singapore for a non-military underground facility. The paper describes the geology of the Underground Science City site and illustrates the layout and plan of the Underground Science City. The geology and rock mass below the Kent Ridge Park is generally favorable for the development of an underground cavern complex. Underground Science City can be potentially developed housed in a cavern complex. Several potential development schemes are studied; with various combination of deep/shallow mined caverns of different span sizes and access options. The preferred scheme is shallow, mined room-and-pillar caverns with large spans and shaft accesses at both existing surface Science Park 1 and Science Park 2. The scheme can be potentially expanded laterally to create more underground space for new Underground Science Cities at Kent Ridge area.

Jan 1, 2001

By Colin Rawlings, Simon Pepper, Maria Karakitsiou, John Mathews, Peter Townsend, Russell Bowler, David Keeble, Christopher Darton, Scott Sadler

National Grid needs to maintain a connection between two existing electricity sub-stations (Beddington & Rowdown) in the Croydon (south London) area, and allow the replacement of two 275 kV cable circuits that are buried under roads. This is to be achieved using a single 400 kV cable circuit within a 10 km (6.25 mile) long, 3 m (9.8 ft) diameter high voltage cable tunnel which is being driven through water bearing Chalk, at depths ranging from 5 m (15 ft) to 80 m (262 ft), with four access shafts(12.5 m (41 ft) in diameter) ranging in depth from 10 m (31 ft) to 40 m (131 ft). The Chalk in this area acts as a source of public drinking water supply (PWS) and is protected by areas designated Groundwater Source Protection Zones. To minimise the groundwater risk the design and construction of the cable tunnel and shafts has paid particular attention to the construction materials used, including testing of these construction materials prior to use, developing construction methods (including the design of the Earth Pressure Balance TBM) and maintaining a groundwater monitoring & testing programme prior to and during construction to ensure the integrity of the Chalk aquifer is maintained as a drinking water source. This paper describes the tunnel &shaft design and construction in relation to these particular groundwater environmental issues which set new precedents for tunnel assessment, design and construction requirements in the United Kingdom.

Jan 1, 2007

By M. Götze, P. Eysel

Over the last years, the importance of the assessment of environmental and social aspects as well as of issues of good governance has increased significantly in mining finance. For this, international standards as well as internal guidelines of the banks and other involved institutions have been established and continuously improved. Considering these standards and regulations, the banks can influence the sustainability of mining projects - and they have done so in the past -, mainly by implementing certain provisions and covenants in the loan documentation, binding the financing to the mining company’s adherence to the agreed sustainability standards. However, there are limits to the banks’ influence due to the competitive environment with other available means of financing. Nevertheless, the experience of the last years has shown that the standards and regulations bound to the financing by the banks help to lead the mining industry towards more sustainable projects.

Jan 1, 2011

By A. K. Majumder

The multi-gravity separator (MGS) is a novel piece of equipment for the separation of fine and ultra-fine minerals. However, the published literature does not demonstrate its use in the separation of coal fines. Therefore, an attempt was made to study the effects of different process variables on the performance of an MGS for the beneficiation of coal fines. The results obtained from this study revealed that among the parameters studied, drum rotation and feed solids concentration play dominating roles in controlling the yield and ash content of the clean coal. Mathematical modeling equations that correlate the variables studied and the yield and ash contents of the clean coal were developed to predict the performance of an MGS under different operating and design conditions. The entire exercise revealed that the MGS could produce a clean coal with an ash content of 14.67% and a yield of 71.23% from a feed coal having an ash content of 24.61%.

Jan 1, 2007

By R. L. Virta

Ball Clay -- Four companies - H.C. Spinks Clay Co. Inc. (owned by Lhoist Group), Imerys Group (formerly Kentucky-Tennessee Clay Co.), Old Hickory Clay Co. and Unimin Corp. - mined ball clay in four states during 2010. Production, based on preliminary data, was 910 kt (1.11 million st) with an estimated value of $42.9 million. That was a 10-percent increase in tonnage from 831 kt (916 million st) with a value of $37.7 million that was produced in 2009. Tennessee was the leading producer state with 61 percent of domestic production. It was followed by Texas, Mississippi and Kentucky. About 70 percent of production was airfloat, 20 percent was crude and 10 percent was water-slurried.

Jan 1, 2011

By Isobel Yeo, Luca Cocchi, Sven Petersen, Nico Augustin, Sean Plunkett, Ingo Klaucke

Exploration for seafloor massive sulfides is currently mainly focused on investigation for active hydrothermal vent fields. However, most of the resource potential is thought to be related to inactive, large deposits that had enough time to accumulate sufficient tonnage. At the same time, ageing of these deposits will ultimately result also in burial acted by either sediments and/or volcanic deposits. We currently lack the technologies to explore for these deposits in a time- and cost-efficient manner. In the fall of 2012 we used a number of AUV-based technologies to explore and image a sulfide occurrence at the Palinuro Volcanic Complex in the Tyrrhenian Sea (Mediterranean Sea; Fig. 1) where sampling and drilling have documented a buried polymetallic barite-pyrite dominated site (Petersen et al., 2014). Sulfide mineralization is here covered by volcaniclastic and pelagic sediments and only red sediment staining and the presence of few tubeworm bushes indicated recent hydrothermal activity - black smoker venting is absent. We used AUVbased high-resolution bathymetry, sidescan sonar imaging, subbottom profiling, as well as magnetics to describe, in a quantitative way, the previously known sulfide-bearing areas as well as to successfully explore for new hydrothermal sites including large chimney structures (Figs. 2). Additionally chemical sensors (CTD, Eh, turbidity) investigated the water column for signs of hydrothermal activity in areas not previously investigated, but at the end, only weak anomalies were found in the southern part of the summit.

Sep 1, 2014

By Christopher J. Bambridge, Lee Seng Hoor

The Stormwater Management and Road Tunnel (SMART) Tunnel is a world first in the use of tunnel space transmitting both road and water through the same spatial envelope. The unique aspect of the SMART project is that the highway decks are used periodically for the conveyance of water. This aspect of the project has posed its own technical challenges that have been overcome in the design stage of the work allowing the project to be taken forward to construction with confidence in the systems to be Installed in the tunnel.

Jan 1, 2005

By James J. Gusek

Passive-treatment systems that mitigate acid-rock drainage (ARD) from coal mines have operating since the mid-1980s. Large systems at metal mines are being contemplated. A 95L/sec (1500-gpm) capacity system is planned this year at an underground lead mine in Missouri. Mine, process and environmental managers need to understand how and why passive-treatment systems work. They must understand what operational limitations to expect, as well as the economics of construction and operation compared to the alternatives, like lime precipitation. Wetlands have been recognized as nature's method of improving water quality. Contaminant reductions can occur through the precipitation of metal hydroxides, sulfides and carbonates and pH adjustments. Local conditions, oxidation state and water and soil chemistries dictate whether these natural reactions will occur under oxidizing (aerobic) or reducing (anaerobic) conditions.

Jan 1, 1995

By V. Kecojevic

Environmental and economic costs related to equipment fuel consumption and carbon dioxide (CO2) emission present a substantial challenge to the mining industry. Haul trucks are an integral part of the overall surface mining system and they consume a substantial quantity of fuel. Consequently, they produce a significant amount of CO2. The objective of this research is to (i) establish a mathematical relationship among a truck?s fuel consumption, power and engine load factors and (ii) determine the amount of a truck?s CO2 emission and the associated cost that may arise from potential CO2 legislation. In order to achieve these objectives we have considered original equipment manufacturer (OEM) haul trucks, commonly used in surface mining operations. The research presented here may be used by mining professionals to help determine the cost and environmental burden of the trucks? application, and efficiently manage energy consumption.

Jan 1, 2011

By D. William Tedder

Several bauxite residue sands and muds produced by Bayer plants in the U.S. and overseas have been fractionated using dry and wet magnetic separators. The magnetic sand fractions typically contain about 60 wt% iron and the bulk of the radioactivity in this waste. The muds are more difficult to process than the sands, but some fractionation is possible using a combination of flotation and magnetic separation techniques.

Jan 1, 1984