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By Gemei Yang, Yihui Zhao

In caved goaf, the friction loss of fluid head is: [h = (R'+ R/Q/ )] Q (for one-dimensional transition flow). The R' and R, which are the functions of two dimensional spaces, are calculated through an empirical formula. Then, the bulking factor and permeability are determined. It is supposed that the airflow in porous media are similar to those in tiny tubes crossing each other. Therefore, the network calculation technique can be used to tackle the field transition flow problem. A lot of case studies showed that the emission of methane in mines mainly depends on the air velocity and has little relation to air pressure. Summing up our experience and experiments, we provide an empirical formula to calculate the gas emission rate per unit area. By means of mass conservation and network calculation, the methane content distribution in steady-state is worked out. Then the dynamic change in airflows and gas content can be analyzed by the characteristic-difference method.

Jan 1, 1987

By Hiroyuki Kawata, Toshiyuki Ueno, Mikio Yamazaki

INTRODUCTION For the construction of several kinds of structures which pass through under railways, we have recently developed an effective and new tunnel construction method, aiming at more secure train operation during the construction as well as the rationalization in the construction works for such structures. Most important in carrying out the construction works for the structures under railways is how to maintain the safe operation of trains. For such construction works, temporary supporting structures and supplemental works have been often applied, for which high cost and long period for the construction have been required. While, this new tunnel construction method has the feature that it is capable of constructing definitive structures for various purposes, which, at the same time, acts as the temporary supporting members for protection of railways. Therefore, this method is now drawing much attention in that higher safety of train operation, low construction cost, and shorter construction period are accomplished, minimizing the period required for slackening the train speed during the construction works.

Jan 1, 1979

By Fredrick J. McGarry, Fred Moavenzadeh

In order to reduce the resistance of hard rocks to excavation by the available cutters, and in order to reduce the wear of the cutters and thus to increase the efficiency of the conventional tunneling machines and to improve their rate of advance in hard rocks, surface active agents have been studied in the controlled laboratory environments and have been experimented with in the field of actual tunneling operations. The laboratory study utilized a notched beam test to measure the effectiveness of 30 different surface active agents on the amount of surface energy required to cause stable fracture in the rock specimens. In addition to the type of rocks, geometry of the specimens, type of surface active agents, the effects of environmental factors such as temperature and degree of saturations were studied. The principle mechanism responsible for weakening of rocks in the presence of surface active agents was believed to be that of stress activated corrosion. The application of surfactants in the laboratory resulted in a reduction of up to 50% in rock strength, while limited experiments in the field have shown a 10 to 20% increase in the rate of advance. Substantial efforts both in the laboratory and in the field are needed to fully understand the mechanism involved and to utilize the effectiveness of surfactants as weakening agents for hard rocks.

Jan 1, 1997

By Robert L. P. Kleinmann

Mining has been a significant component of the Appalachian economy for about 200 years. The region continues to be adversely affected by the environmental degradation associated with these past activities. In addition, companies today are being denied permits at sites where acid generation appears likely. And air emission limitations at power plants now threaten the economic health of many moderate- to high-sulfur coal mines. Thus, when considering the environmental impacts of mining coal in Appalachia, it is important to consider abandoned and active mine issues. For example, abandoned mines generate acidic, iron-rich waters that adversely affect more than 6,400 km (4,000 miles) of rivers and streams in Appalachia. In contrast, operations that were active after the enactment of the 1977 Surface Mining Control and Reclamation Act (SMCRA) cause little water pollution. However, the costs of water treatment at such sites exceed $1 million a day. Even where water quality is not dimished, water supplies can be affected by mining. Subsidence-induced fractures can lower water table elevations or drain a surface stream dry. Subsidence can also cause damage to surface and subsurface structures.

Jan 1, 1995

By Steve Vaughan

Canadian Regulation and Reporting Requirements High reporting standards are essential in developing and sustaining a strong confident capital market. As of February 1, 2001, technical reports on mineral exploration and mining work, must conform to the standards of the Canadian Securities Administrators (CSA) National Instrument 43-101. Only a ‘qualified person’ may supply the technical information on which a news release is based and must verify that the final version of the release is accurate.

Jan 1, 2003

The challenge of the sustainable development framework in mining today is to see that the minerals sector as a whole contributes to human welfare and well-being without reducing the potential for future generations to do the same. If the minerals sector around the world is to contribute positively to sustainable development, it needs to demonstrate continuous improvement of its social, economic, and environmental contribution, with new and innovative governance systems. Canada is an international leader in mining and related technology. Metals and minerals is Canada?s second-largest earner of foreign exchange. Canadians, along with the rest of the world, are increasingly concerned about the environmental impact of mining activities. The Canadian Mineral industry has acknowledged the importance of its environmental responsibility by taking a broad range of innovative actions in order to ensure a sustainable development of its resources. This paper analyzes how the concept of sustainable development can be related to mineral enterprises. It discusses a wide range of issues under three main areas: perspectives on sustainable development; processes for furthering sustainable development; and assessment methodologies and indicators. This paper also presents a proposed framework and a core set of key sustainable development indicators that could be useful in efforts to measure progress toward sustainable development in mining. The paper concludes with a case study of some key sustainable development indicators related to the Canadian oilsands mining.

Jan 1, 2003

By P. R. McOllough

The Colorado Department of Highways awarded a contract to construct the Second Bore of the Eisenhower Tunnel in August, 1975. The contract was completed June 29, 1979, nine days ahead of schedule, with¬out major claims or delays. The tunneling involved complex construction through difficult ground conditions. The contract, plans and specifications were specifically planned to more equitably share the risks involved and to minimize adversary relationships. The Department produced a detailed tunnel design and maintained responsibility for the design. The contract employed some new provisions; e.g., a review board for settlement of claims and disputes; escrow documents (contractor's bid documents) to determine the contractor's basis of bid when determining adjustments. The tunnel contract, plans and administrative efforts employed by the owner and contractor were very successful in this project.

Jan 1, 1981

By Thomas F. Martin

Contract 75-124-211 extends along the Chicago River from Roosevelt Road on the south to Ogden Avenue on the north. In addition a branch tunnel runs east from approximately mid-project ending near Lake Michigan. The contract was bid on December 14, 1977 with three joint-ventures submitting bids. Of these the joint venture of J.F. Shea Co., Inc. Walnut, California, (Sponsor), Peter Kiewit Sons' Co., Omaha, Nebraska and Shea Company and Associates, Walnut, California was low with a bid of $101,976,680.00. The MSD awarded the job to the Joint-Venture on January 5, 1978 with a scheduled completion date of January 23, 1983. The project consists of the following major items of work: (1.) A 25'-0" minimum diameter Construction Shaft, 220 feet deep (2.) 13,726 Linear Feet of 30'-0" Concrete lined Tunnel in rock (3.) 6,648 Linear Feet of 13'-0" Concrete lined Tunnel in rock (4.) Seventeen concrete lined Drop Shafts varying in finished diameter from 4'-0" to 12'-0", and each approximately 250 feet deep with chambers and connections to the tunnels varying from 100 to 1300 feet in length.

Jan 1, 1979

The present study refers to passive systems for the treatment of acidic liquid effluents emanating from mixed-sulphide mines by means of an-aerobic compost wetlands. An effort was made for the thermodynamic study of the chemical systems that are involved in the reactions during the simulation of this specific system using laboratory columns and a pilot scale application. The substrate used was a mixture of cow manure, a high alkalinity organic substrate and chestnut woodchips, while the synthetic solutions prepared for the laboratory experiments contained the three basic metal contaminants i.e. Fe, Zn and Mn. The precipitation mechanism of the contained metals and the form in which these are precipitated was therefore investigated by constructing the equilibrium phase diagrams (Eh-pH diagrams) of the Me-S-C-H2O systems. Based on the experimental results from laboratory and pilot scale tests the stability conditions of the chemical species taking part in the aqueous solutions were also determined and verified with the thermodynamic data available. The thermodynamic analysis of the system was performed for ambient temperature, which is the prevailing temperature on field constructed compost wetlands. Results were further validated with the results obtained by the application of a five step sequential extraction procedure in the remaining substrate in order to determine the form in which the metals were precipitated.

Jan 1, 2006

By Osamu Shoji, Mamoru Kato

In order to continue improving the quality of telecommunication services to meet the expectations of the people and to increase reliability in the case of emergency such as disasters, Nippon Telegraph and Telephone Public Corporation (NTT) is now constructing cable tunnels which connect main urban telephone offices. However, almost all the large cities in Japan are built in river deltas, so that their chief underground features are low strength fluvial deposit and a high ground water level. In this saturated soft ground, the ground surface at an installation site has occasionally subsided through deep excavations for cable tunneling construction. As these settlements have sometimes caused accidents, especially in densely populated large cities, NTT has made much effort to avoid such accidents. These accidents have occured mainly in flexible sheeting due to its inward movement. Therefore, after the investigation into forecast method of sheeting deflection with accuracy, NTT has reserched a system which forecasts ground surface settlements. This paper describes an outline of the ground settlement forecast system and practical example on the site.

Jan 1, 1979

By Donald B. Larson, Milton Finger

The use of explosives in deep rock mining carries conventional blasting technology into a relatively new and unexplored realm. Although bill ions of pounds of explosives are used fairly routinely in mining, quarrying, and construction, almost all of these uses are surface blasting. Most of the in sib processes that are proposed for recovery of mineral or energy resources require the creation of high permeability to provide well defined flow paths in the resource bed. At present there is very little information on the fracturing produced by explosives deep in the earth, and the technology for using explosives in deep rock mining is just evolving. A qualitative understanding of the applicable mechanisms in deep rock fracture leads to some key parameters in the selection of explosives for deep rock mining. The selection and characterization process involves a careful analysis of the field environment and the establishment of tests to determine candidate explosives response to planned and accidental stimuli. The details of this selection and characterization process are given for a few candidate explosives. The use of explosives in deep rock mining must be considered as one of the possible tools for recovery of yet untrapped energy and mineral resources. A basic understanding of explosive deep rock fracture will allow optimum selection of explosive processes or other more appropriate methods for recovery of energy or minerals from a particular resource area. The results of some experimental studies are discussed.

Jan 1, 1977

By Michael Beyer

Following the last Cholera Epidemic in 1872, resulting in approximately 400 deaths, the City Council of Munich decided to re¬place the former water supply system within the city limits by tapping new water supply areas outside of the city. Since 1883 Munich has been obtaining its water from the Mangfall River catchment located some 35 km to the south. Its most distinguishing characte¬ristics are as follows: 1) the water is free-flowing, i.e., a pumping system is not required as the catchment area is 100 m higher than the city; 2) the water does not normally have to be treated, meaning "spring fresh" tap water. On a daily basis, 300,000 m3 of water flow through the more than 100 year old pipes, accounting for 70% of the city's daily need. There was originally no requirement of a water tight system as strategically installed drain pipes prevented the build-up of exter¬nal water pressure on the lining. As the qua¬lity of today's water has become significant¬ly worse, the tunnels are now in dire need of restoration or replacement.

Jan 1, 1995

By M. Di Tommaso

Acid Mine Drainage (AMD) is a quite diffuse environmental problem in dismissed sulphur mine districts. AMD is related to sulphur oxidation of abandoned tailings, generating heavy metal-bearing streams with high iron and sulphate contents and low pH. Treatments of AMD aim firstly to increase the pH to reduce its leaching power causing the further release and mobilization of heavy metals through soil solution and groundwaters. Increasing the pH also allows the precipitation of iron (III) (involved in sulphur oxidation and then in AMD generation) and the partial removal of other toxic components such as arsenic. pH adjustment and the reduction of the high concentration of iron are also necessary for the successive biological treatment in permeable reactive barriers (PRB) with sulphate reducing bacteria (SRB) (II step, biologically mediated precipitaton/biosorption) to avoid the rapid plugging of the barrier (for the large amounts of iron precipitates) and to ensure neutral pH conditions for SRB growth. In this work the first step (chemical precipitation) of a combined chemical and biological treatment of AMD is presented. Experimental data from column tests using carbonate stones to remove iron and increase pH were reported. Toxicity tests have been carried out on the treated wastewaters by Lepidium sativum.

Jan 1, 2006

By Yuanping Chen, Yihui Zhao, Yunhe Hong

It is important to study the methane transport phenomenon in a longwall panel under descentional ventilation conditions. The gob area is divided into a number of rectangular percolating elements, each of which is connected with its neighbors by leakage passages, so that a network can be formed. Using the mechanics of porous media fluid flow, the mathematical model of air and gas flows can be established. Based on the existing ground pressure theories, the inhomogeneous porosity of the porous media in the gob can be given. Through computer simulation it is found that air pressure and temperature are functions of position. Air density, viscosity, and natural ventilation pressure are functions of temperature, pressure and methane concentration. It is also found that the resistance varies with air density and viscosity. Finally, the calculation results are given to show the differences between ascentional and descentional ventilation methods.

Jan 1, 1991

By M. A. Bronston

A drill system configuration capable of working in the arctic offshore environment was developed to evaluate the placer gold resources contained in the glacio-fluvial sediments offshore Nome, Alaska. This system is capable of working on the shore fast ice during the winter months and is deployed on a drill ship during the summer. Transfer of the drill between its summer and winter configurations is accomplished with a minimum of modification to the design. The system is designed around the Becker drill. This percussive, reverse circulation drill is capable of penetrating the indurated glacial sediments present in the offshore Nome environment. This drill has operated effectively to depths in excess of 50 m (164 ft) below sea level. Since early 1987, in excess of 2000 holes have been drilled using the system. The drill system often operates in extreme weather conditions. It has averaged approximately 10 holes a day of drill production. The ore reserves defined during these drilling programs have resulted in the recovery of more than 70,000 oz (2.18 t) of gold to date, by the mining vessel Bima.

Jan 1, 1990

By George A. Hoffman, Richard J. Proctor

INTRODUCTION We will discuss here only the subway construction phase; that is, two to five years at a given location--not the long-term analysis. We also will compare some tunnel construction methods used for BART and in Los Angeles. Typically, urban planners and engineers try to balance a new mass transit system to include tunneled subways, cut-and-cover construction in city streets, and elevated guideways. Their decisions are based on many factors, most of which can be quantified. But there are some socio-economic-environmental factors which are almost intangible, or nonquantifiable, and these are rarely included in the final report for a rapid transit system. There are two reasons for this: First, it is difficult to evaluate disruptions and psychological inconveniences to individuals and to the community during the construction period, and even more difficult to assign costs because the valuations are always subjective. Second, the rapid transit project capital costs are given in the final report and the public knows them; but the intangible social costs are borne by the affected neighborhood community, not the entire city, and as such they are "hidden costs," which in fact may add as much as 25 percent to the total system cost.

Jan 1, 1974

By Don Rose

I. INTRODUCTION The Atlanta Research Chamber is an UMTA-sponsored applied research facility studying tunnel design, excavation and support systems. It is located directly below Peachtree Street in downtown Atlanta, Georgia. It is included in the CN-120 contract to build the Peachtree Center subway station, a part of the Metropolitan Atlanta Rapid Transit Authority (MARTA) multi-billion dollar "Phase A" 53-mile transit project, which is 80 percent funded by UMTA with 20 percent provided by local authorities in Atlanta and Fulton and DeKalb counties (Figure 1). The Research Chamber is located immediately south of the main Peachtree Center Station cavern, and is in part an enlargement of the pre-existing Pilot Tunnel excavated to provide bidders on the CN-120 contract a view of the rock conditions (Figure 2). The Research Chamber lies some 3 meters above, and is approximately parallel to, the twin Running Tunnels. The Research Chamber is 18 meters long and has the same 5.5 meter diameter horseshoe shape design dimensions as the twin Running Tunnels.

Jan 1, 1979

By James S. Redpath

INTRODUCTION Background Early in 1972 our firm was asked by Cominco, managers of Arvik Mines Limited, to carry out an underground exploration programme referred to as the "Polaris Project" on a zinc-lead deposit in Canada's High Arctic. We had carried out numerous projects in the far north but this was to be the first long decline driven in perma-frost. Despite the short notice it was possible to meet the quickly approaching summer shipping deadline. We were able to do this by drawing heavily on our own and Cominco's background in Arctic operations. The project was an excellent example of owner-contractor co-operation and this spirit was responsible for the success of the project. Unusual Aspects There were a number of unusual aspects of the Polaris Project which are discussed in this paper. The extremely remote location, the short shipping season, and the fact that the work was carried out in permanently frozen ground, when combined with the lack of handy fresh water and a very severe climate, make it unique in many respects. Despite these handicaps, a record was set during the driving of the exploration decline.

Jan 1, 1974

By Keith Whiting

The Van Stone zinc-lead mine is located in northeastern Washing- ton in Stevens County. It is about 24 km (15 miles) south of the Canadian border and 48 km (30 miles) west of the Idaho line. The deposits occur in late Cambrian age limestones and dolomites of the Metaline Formation. The bedding controls the trend of the zones containing the lenses of zinc-lead mineralization. The Van Stone property and vicinity is almost entirely covered with glacial drift averaging perhaps 6 m (20 ft) in thickness. Outcrops are very sparse. Outcropping gossan with zinc mineralization was first discovered by George Van Stone in 19 13, in what is now known as the South Ore Zone. Only minor trenching was done at that time. The property was idle until the mid- 1920s when Hecla Mining Co. drove several short adits and performed minor diamond drilling. In 1938, Willow Creek Mines of Nevada Inc. acquired the Van Stone plus adjacent parcels and commenced drilling on the known South Ore Zone. In the course of an expanded drilling program, the nonoutcropping North Ore Zone was discovered and was drilled out along a N30°E strike for about 305 m (1000 ft), beyond which point no mineralization was intersected.

Jan 1, 1991

By H. T. Mikkelsen

Mineral production implies emissions of particulate matter (dust), noise and vibration that may cause conflicts with neighbors living nearby. In Norway a few conflicts has been brought to court, the latest in 2006. This paper discusses dust emissions and dust depositions (dustfall). The pollution authorities have accepted monitoring of dustfall instead of suspended dust as the first step in conflict cases concerning small and medium sized enterprises. In the case of exceeded limit values, the second step is to require monitoring of suspended dust and next the implementation of control actions to reduce dust emissions. Dustfall monitoring programmes carried out at six mineral production plants in Norway, show that the mineralogical rates of dustfall are rather low a few hundred meters away from the plants or the tailings disposal. They are mostly considerable lower than the limit value of 5 g/m²/30days accepted by the authorities. Seasonal variations between mineralogical and organic dust fractions can be observed in Norway, with higher content of mineral dust during winter time. Other sources to mineralogical dust can be recognized. During winter time wear of road pavement and sand on icy roads can give high emissions of mineralogical dust to the ambient air. Parallel monitoring of suspended dust and rates of dustfall indicate that dustfall can be used to estimate the level of suspended dust. A model for estimating suspended dust based on records of dustfall is presented.

Jan 1, 2007