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By A. D. S. Gillies

The use of refuge chambers for use in handling underground emergencies is an issue of topical relevance within the US mining industry. Chamber design is of importance to meet some new safety requirements of US federal and some state government mine regulations. A review has been undertaken of a steel mine refuge chamber design to predict what will be internal temperature within the chamber over an extended period with miners present? The design has been examined for the situation when the chamber is sited in still mine air. Spreadsheets have been developed to allow various design assumptions to be tested. The evaluation has been undertaken using thermodynamic heat transfer models with some assumptions specified to produce a model of appropriate simplicity but with adequate degree of accuracy. Under normal still air conditions it can be seen that internal chamber conditions rise quickly to often arduous conditions. There will always be quite a few assumptions necessary in complex heat transfer process evaluations. Some important refuge chamber design parameters are: ? External surface area of the chamber, its wall thickness and construction. ? Metabolic heat generated and number of persons making use of the chamber. ? The temperature of the external mine atmosphere to the chamber over the year and the influence of geothermal gradient on temperature at depth. ? The maximum internal chamber Apparent Temperature considered safe. ? The distance inside the underground mine and adjacent ventilation conditions.

Jan 1, 2012

By Keith Schaeffer

This paper presents a history of the planning, engineering and construction completed for the railroad tunnel crossing part of the West Elizabeth Avenue Storm Drainage Project, undertaken to relieve flooding within the West Elizabeth Avenue area in Linden, NJ. The Railroad Crossing Contract is part of the larger Linden Drainage Improvements Project consisting of a new gravity storm sewer system. The improvements are required to provide additional storm drainage for the City of Linden and the Merck Pharmaceuticals manufacturing facilities in the City of Linden.

Jan 1, 2008

By P. R. Clifford

Phosphogypsum is a byproduct of the manufacture phosphoric acid. There are approximately one billion tons of phosphogypsum stored in stacks in northern and central Florida. The Florida Institute of Phosphate Research (FIPR) is investigating potential uses of phosphogypsum. These include using phosphogypsum as a road base material, as a soil amendment in agriculture, as a daily cover in landfills, and as a construction material. The results of this research will be presented and will be discussed in light of regulatory barriers to the use of phosphogypsum.

Jan 1, 2002

By Andrew K. hg` Officer, A. L. Griffiths, J. Andrew Hindmarch, Gert Wittneben

Durban Harbour in South Africa is one of the continent’s busiest ports however the harbor entrance is currently too small for the new generation of container ships. There-fore it is to be deepened and widened by the National Ports Authority in the near future. An existing immersed tube tunnel carrying major sewer, water and other utilities under the harbor first needs to be removed and replaced by a deeper 4.4 m ID ser-vices tunnel. Construction of the deeper tunnel saw the first use of a slurry machine in South Africa and was required to negotiate grades up to 20%.

Jan 1, 2007

By Gene Mattila, Ron Boyd

Introduction Rock bolting is a general term that encompasses pinning, roof bolting, rib bolting, and cable bolting. Rock bolting contributes the highest nonproductive cost and is the most significant safety risk in mining today. Total installed bolt costs are now more than $20 per bolt. Rebolting or repair work doubles this. And bolting accidents account for about 30% of all fatal and nonfatal lost time accidents. It is only logical, then, for the mine operator to install the highest quality anchors possible. Every bolt on the market - tensioned, untensioned, full contact, or point anchor - has designed capabilities in axial, shear, and fluctuating ground conditions. Bolts will provide a designed support if material specifications and installation procedures fall within the manufacturer's recommendations. This also assumes that there are no unexpected geological or operational changes. Proper material specifications and installation procedures should guarantee the mine operator a quality anchor. To help assure this, the Mine Safety and Health Administration (MSHA), the US Bureau of Mines (USBM), and the AMC Manufacturers group developed stringent ASTM materials standards. These govern mechanical point anchor bolts and bolts using threaded and nonthreaded rebar. There are also minimum standards that suppliers must comply with in the manufacture of frictional bolts. However, most frictional bolt standards are based on the manufacturer's own specifications. It would be impossible to set uniform regulations on frictional bolts. Each bolt provides support in a slightly different manner and thereby requires different material needs. Quality Control In any case, material quality can generally be assured through tight order specifications and periodic quality control checks. The problem with installing quality anchors does not solely lie with the material. It includes all the events that occur from the time a bolt leaves a manufacturer to the time it is installed. The anchoring ability of any major type bolt can be affected by transportation, storage, mechanical performance of installation equipment, installation demands of the operator, proper drilling accessories, and local geology. Table 1 and Fig. 1 document the negative events that can affect each bolt and the degree to which it can be affected. Drilling a hole of oversized diameter, for example, is an operator controlled factor. It will adversely affect most bolts. An over-sized diameter reduces, or even eliminates, the anchorage capability of a mechanical shell. It will reduce the support capacity of a split set to nearly nothing. And it will cause a partial or incomplete grouting around the resin bolt. Frequently, due to bit wear, holes are drilled undersized in diameter and may not be properly cleaned out. In this case, it will be difficult for the operator to push the mechanical shell into the hole, thereby causing him to drill another hole. In cases where the bolt is obviously not providing anchorage, operators will probably drill another hole and place another bolt. Rock Bolt Regulations It is the situations where a bolt is improperly installed in the hole, but gives the appearance of a good bolt, that are frightening. In fact, some safety officials and engineers believe that only 50% to 60% of installed bolts are working. These bolts cause irregular ground load transfers in other bolts and overload them. This causes hazardous situations and overstressing. It is these bolts that fail prematurely 200 to 255 mm (8 to 10 in.) behind the face and possibly contribute to the high accident rate. The government and several manufacturers recognized the need to check the integrity of rock bolts. These programs are in different stages today. Tight torque regulations have been established for mechanical

Jan 4, 1985

By Mitchell L. Fong

The Bay Area Rapid Transit (BART) District will be extending BART service south along an 8.7-km (5.4-mile) -long corridor in the city of Fremont, California as part of the Warm Springs Extension (WSX). The WSX project will link the existing BART system to the future BART to San Jose extension. A segment of WSX is located in Fremont Central Park (referred to as the Fremont Central Park Subway Project). The Fremont Central Park Subway is considered the most complicated and geotechnically challenging portion of the project with an underground subway box being constructed near the active Hayward Fault which is capable of ground motions up to 0.75 g and is located in an aquifer which is used for water storage and supply. Soil-structure interaction analysis was used in the design of the subway box to resist deformations due to earthquake ground motions. A water-tight excavation support system has been designed to allow subway box construction while minimizing impacts to the aquifer.

bauma 2004 will feature a couple of firsts for one of the world’s largest construction and building materials machinery exhibitions. The event is scheduled for March 29 through April 4 of next year at the New Munich Trade Fair Center in Munich, Germany. For the first time, bauma will feature an exhibition area dedicated to mining equipment and technology. Also for the first time, the Commonwealth of Independent States (CIS) will be a partner region of bauma.

Jan 1, 2003

By Thomas P. Kwiatkowski, Joginder S. Bhore, Christopher D. Orlandi, Jose Velez

Three case histories of successful TBM tunneling for New York City Water Tunnel No. 3 are presented. The tunnels, costing about one billion dollars total, are the 5-milelong, 18'-11" OD Brooklyn Tunnel; the 5-mile long, 23'-2" OD Queens Tunnel, and the9-mile long, 12'-4" OD Manhattan Tunnel. The three tunnels are the first major tunnels constructed in New York City rock utilizing the TBM method of construction. This paper describes and compares the three tunnel projects in terms of geology, construction methods, TBM’s, rock and groundwater behavior, rates of advance and other performance data, and challenges and solutions encountered during the projects.

Jan 1, 2007

By Charlie Watts, Ken Smales, Ron Fleming

The Manapouri Power Station is an underground hydro-electric station located in the South Island of New Zealand, and was constructed in the 1960s. Between 1997and 2002, a second 10m diameter tailrace tunnel was constructed to increase the out-put and to improve the overall hydraulic efficiency and output of the station. A critical economic and project approval consideration for the second tunnel was the outage time required for the breakthrough into the power station. The power station is in part dedicated to providing power to an aluminum smelter with the balance to the National Grid, and apart from the physical problems associated with providing an alter-native power supply to the smelter, the loss of generation revenue and supply risk were significant issues. Innovative planning reduced the planned outage time from several months to21 days, and the breakthrough was eventually achieved in 11 days as a result of additional value engineering measures implemented during construction. This paper describes the engineering optimization that took place during the planning stages of the project and later during construction, as well as describing the construction methodology used.

Jan 1, 2007

By Peter Campi, Harry R. Asche, Ian P. Callow, Edmund G. Taylor, P. Scott Smith

The US$1,850 million EastLink project is a 39km tollway and includes twin 3-lane,1.5km long, undrained driven tunnels. The hard rock tunnels are being built to avoid passing the motorway through the Mullum Mullum Valley and so to help preserve the unique flora and fauna in the area. This paper describes several of the key issues in the tunnel design and construction, including: the integration of the temporary support design with the Contractor’s tunnel excavation and support procedures, including sharing of responsibility between the Designer and Contractor for support type selection and the production of a project specific rock mass classification system to enable more objective determination of ground conditions. detailed hydrogeological assessments during the design and construction phases to allow confirmation of design loads for the tunnel lining design and the various suite of waterproofing tools in order to meet the project inflow requirements. development of a pre-cast invert solution to the main tunnel secondary lining to enable faster lining construction and to minimize risks to the tunnel membrane associated with fixing reinforcement and construction traffic.

Jan 1, 2007

By John S. Hutchins, David L. Wassum

Mining engineers are ready to take a big step into a new field-oil mining. To understand the subject, one must look at the world's oil supply and demand as well as petroleum technology successes and failures. The US has an abundance of solid hydrocarbon and uranium energy resources, but 75% of its energy for industry, transportation, manufacturing, and space heating comes from liquid petroleum and natural gas. So there are increasing efforts to discover new oil reserves; today the number of drilling rigs operating in the US is at an all-time high. But with 80% of the world's wells already located in the US and Canada, good new exploration prospects are difficult to find. The cost of drilling deep new wells has also greatly increased. The US faced a similar situation in the early 1950s, when primary oil production declines began. During that time, the petroleum researcher introduced secondary recovery techniques such as water flooding and gas injection. This increased the average amount of extractable oil from discovered US reservoirs from 17% to 33%. Production soared and the world petroleum price remained stable until the end of the 1960s. Secondary recovery techniques were then supplemented by tertiary oil recovery technologies-increasing sweep efficiency with such things as CO2 injection-that are, so far, only partially successful in most petroleum fields. Even so, these technologies could raise cumulative recovery expectations to 35-38%. The "lost" oil in depleted US reservoirs equals 48 km3 (300 billion bbl) of conventional oil, or 12 times the current recoverable reserve base. At the present rate of US consumption-1 km3/a or 6 billion bbl/a-this is enough to run the US for 50 years without importing any oil. Moreover, there are 16-24 km3 (100-150 billion bbl) of as-yet unrecoverable heavy oil and tar sands in the US.

Jan 12, 1981

By B. Das

Hematite floatability from two low grade banded iron ores of India, namely banded hematite quartzite (BHQ) and banded hematite jasper (BHJ) using fatty acids and amine as the collectors is investigated under identical physico-chemical conditions. The results indicated that hematite present in BHQ ore is easy to float using both the collectors, compared to BHJ ore. The difference of flotability between the two banded iron ores is that quartz grains are coarser and well liberated below 100 micron size in case of BHQ compared to BHJ ore. In case of BHJ ore, fine hematite and quartz grains are intimately inter-grown and are dispersed in thick jasper bands leading to liberation problems. Besides that, dusty jasper particles coat over hematite surface in case of BHJ ore during the process of grinding, which hinders specific adsorption of collector on hematite or quartz surfaces. This is substantiated by scanning electron microscopy (SEM). The flotation studies have indicated that it is possible to achieve ~64% Fe with ~67% recovery from a BHQ ore using both anionic and cationic collectors from a feed containing around 38% Fe. In contrast, the hematite recovery in BHJ ore was poor. Differences in the ore characteristics that affect the flotability of hematite present in both the ores are compared. Keywords: Banded hematite quartzite, banded hematite jasper, flotation, oleic acid, dodecylamine, QEMSCAN, Scanning electron microscope

Feb 27, 2013

By Steve Kral

In a lagging economy where profits are tight, businesses cut costs. No revelation there. The mining industry, though, has always looked for ways to reduce production costs — no matter the state of the economy or commodity prices. The fact is, when planning a new mine or the expansion of an existing one, mining companies gamble that commodity prices will be reasonably high when a project comes onstream. It takes millions of dollars and several years to bring a mine into operation. And a lot can happen economically between the time management gives the go-ahead for a new project and its completion.

Jan 1, 2002

By Harry R. Price, Behrooz Tahmasbi, Charles J. Roarty

The 2,408 meter (7,900-foot) long Middle Rouge Parkway Interceptor Extension varies in size from 1.52-meter (5-foot) to 2.36 meter (7-foot 9-inch) inside diameter. Most of the sewer was constructed in tunnel through fine sands and silts. Piping of these soils through the concrete liner eventually resulted in a loss of soil support, settlement and/or severe distress of the sewer, and the formation of several sinkholes. The repair and restoration was generally performed in the sewer and included cast-in-place concrete, shotcrete, cured in place pipe, soil stabilization, cement grouting, dewatering, and chemical grouting. As a part of the work, temporary pump stations and flow diversions were required to perform the work while minimizing discharges to the adjacent Rouge River.

Jan 1, 2007

By C. Bazin

The separation of rare earth elements is a complex process that is industrially carried out using liquid/liquid extraction. Detailed flow sheets of solvent extraction plants for the separation of rare earth elements are rarely available in the literature which limits the opportunity to teach and test the application of data reconciliation, process optimization and control to these types of plants. The basis of a simulator for a rare earth elements separation plant is described in this paper. The simulator is used to adjust the organic phase and stripping acid flow rate in a separation circuit of heavy rare earth elements from light one?s.

Feb 27, 2013

By Yoshinori Iwasaki, Shosei Serata, Yutaka Mochida

A new comprehensive insitu instrumentation technique named this RCC Method has been developed for rapid assessment and improvement of the structural stability of underground openings. When applied to tunnel construction, the degree of present and prospective safety of underground openings can be determined in quantitative terms within 10 to 20 minutes of microcreep observation. When applied to mining, roofs and floors can be stabilized by controlling the stress conditions. This stress control method has eliminated the need for intensive roof bolting and extensive floor renewal in all cases where it was applied. Use of this technique is illustrated by field examples from the Seikan Undersea Tunnel of Japan and deep potash mining in Canada. NEW INSTRUMENTATION TECHNIQUE: THE RCC METHOD Failure problems in underground excavation usually arise in weak non-elastic grounds where conventional rock mechanics theories of elasticity are not only useless but also misleading. Presently, discontinuity planes in the ground are being considered a factor in assessing these failure problems, and while this development is interesting academically, it is not of much use in actual excavation work, where it is nearly impossible to identify and quantize all existing planes of discontinuity. Even if such an extraordinary task could be accomplished at an underground excavation site, effective use of the data would be difficult and impractical for rapid excavation work, with the possible exception of rare cases of ideally elastic ground.

Jan 1, 1976

By Brad Murray

Evaluating the performance of a shielded tunnel boring machine (TBM) can be difficult because the ground cannot be observed directly and in relation to the TBM attitude within the excavation. It is difficult to determine whether performance problems are caused by ground loading, steering issues, fine muck packing against the shield, or migration of annular grout around the shield. The Arrowhead Tunnels Project in Southern California uses strain gauges on its shielded hard rock TBMs to detect shield strains early and correlate them with tunneling conditions, thereby increasing the chances that problems will be correctly diagnosed and addressed to optimize TBM performance. The frequent automatic measurement of shield strain has also been valuable by confirming whether remedial methods used to free the machine after stoppages are effective. This paper discusses the qualitative interpretation of characteristic strain patterns on the Arrowhead Tunnels TBM shields and discusses installation details and special considerations for setting up a strain measurement system.

Jan 1, 2008

By Andrew Howard

As the mining industry moves further into developing countries in search of new resources, its role in international development is coming under increasing scrutiny. This is a trend that is likely to accelerate, along with the potential for headaches among managers in the industry. Public interest in development and environmental issues is rising as faith in “big business” falls. This has strengthened nongovernmental organizations (NGOs) campaigning for sustainable development. And it has put more pressure on banks, governments and development agencies to curb corporate misdemeanors. Developing world governments are also becoming emboldened to reject previously agreed terms they do not consider equitable. The mining industry has begun to formulate a response to these pressures but must go much further. Societal and environmental issues must move from public relations to core strategic thinking. Abiding by rules or codes is not a relevant response. Instead, genuine support for sustainable development is required. This will involve delegating the responsibility for engaging with local communities to on-the-ground staff and developing a dialogue with local stakeholders rather than conducting an initial assessment and disengaging.

Jan 1, 2006

By R. E. Mitchell

Environmental Impact Assessment (EIA) is the accepted method for evaluating proposed mining and other industrial projects to obtain regulatory approval and to help companies plan for responsible development. Another evaluation system becoming increasingly more common for proposed projects is the Environmental, Social and Health Impact Assessment (ESHIA). An ESHIA differs from an EIA for its more comprehensive and inclusive approach to evaluate potential impacts on public health, and its ecosystem services approach to assessing biodiversity impacts. An ESHIA may also be required by certain lenders for financing major projects. Conducting an ESHIA for a proposed mining development is not without its challenges, with costs, scheduling, regulatory concordance and other constraints to be considered. This paper examines some benefits and challenges of ESHIAs and summarizes lessons learned using a case study approach.

Jan 1, 2012

By F. Dahl, P. Raleigh, J. Holzhauser, B. Nilsen

Tunnel excavation using tunnel boring machines (TBMs), has become increasingly common in recent years, despite the fact that precise evaluation of certain risks have not kept pace with the use of these machines. One of the risks easily overlooked by Engineer and Contractor alike are the effects of abrasive ground on the costs and schedule of a given project. The impacts of worn and damaged TBM cutter heads have been observed on hundreds of tunnel projects around the world. It would appear that a reliable prognosis of the abrasiveness of soils on a project would be of great importance for designers, clients and contractors alike. Several well acknowledged test and prognosis methods already exist for rock, however there is only very limited knowledge available to describe the abrasiveness of soil and its impact on soft ground TBMs. This paper will examine approaches to this problem and suggest a new approach based on a current project undergoing design.

Jan 1, 2007