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By Heflin. L.

The Washington Metropolitan Area Transit Authority, WMATA, has constructed over 92 revenue miles of rapid transit facilities including some 14 miles of rock tunnel and 12 miles of earth tunnel. The system map is shown in Figure 1. During construction it is not unusual for contractor to encounter ground conditions resulting in major problems and extra cost. Problems such as major rockfalls and a "stuck" boring machine in squeezing rock are not unusual. In recent years, faced with additional tunnel construction projects, the Authority has sought newer tunneling methods which might be less costly. One new method which has been tried is NATM, the New Austrian Tunnel¬ing Method. NATM, which is applicable to both soft ground, mixed face and rock tunneling, relies on miners and comparatively small machines to excavate in conventional ways, but it is unique in its methods of obtaining "stand-up" time at the excavated face and its method of using shotcrete as an initial lining, frequently with a drainage system to reduce hydro-static pressure on the final lining. Lower costs result from use of a cast-in-place concrete liner, and from a reduction in the number of work operations at the mine heading which provides better daily production. WMATA has recently completed three twin bore tunnels constructed by NATM technology. The first was the Wheaton Tunnel and Section, followed by the tail track tunnel to total some 4200 linear feet cut through jointed rock up to 270 feet below ground surface, and the last was in soft ground at Fort Totten. A

Jan 1, 1993

By Steve Kral

The power industry throughout the world is in the midst of a significant transition that will result in a major restructuring. Deregulation of utilities in the United States is continuing, resulting in increased competition among power providers. The traditional ways that electric power is globally bought, sold and delivered will also change. However, according to the Department of Energy's (DOE) Pat Godley, one thing is clear: "Those who provide the power during the 21 st century will be those who are willing to change - those who are willing to accept new ways of doing business and willing to employ new technologies." Godley is assistant secretary of fossil energy with DOE. Her comments came during the opening remarks at the Fourth Annual Clean Coal Technology Conference, held in Denver, CO, Sept. 5-8, 1995. The conference was sponsored by DOE and the Center of Energy and Economic Development. Under the theme "Global Opportunity," more than 300 coal and utility executives spent three days discussing the new face of the electric-power industry throughout the world and the new, mostly clean coal technologies (CCT) that will be available to power providers.

Jan 1, 1995

By Steven W. DeCou, Marcus R. Jensen, Stephen Navin

The Lake Mead Intake No. 2 is a project constructed for the Southern Nevada Water Authority which includes a 12-foot diameter lake tap and intake shaft constructed in over 225 feet of water; 1650 feet of 16x14-foot horseshoe-shaped tunnel leading to a forebay that is 165 feet long, 35 feet tall, and 30 feet wide; twenty-two 4-foot diameter steel lined well shafts extending 325 feet from the ground surface to the forebay; 3500 feet of 12-foot diameter pipeline crossing a bay in Lake Mead that has water depths of up to 80 feet; and 2700 feet of 9-footdiameter steel-pipe-lined tunnel. Major site grading for a future pumping station in the area above the forebay is also included as part of the project. The project is on the schedule’s critical path for completing the first phase of a $2 billion water supply program for the Las Vegas Valley. In this paper, the owner, the designer and the construction manager present a discussion of the risk management strategies that were used to control costs, minimize project delays, and facilitate problem resolution. The discussion includes an assessment of the effectiveness of the risk management strategies in meeting these objectives. This paper will be of interest to owners and engineers planning underground projects, especially those projects that present unique risks during the construction phase.

Jan 1, 1999

By L. G. Austin

Equations are derived to allow for different mean velocities of axial flow for different sizes of particles in fully mixed ball mills. The equations are modified to allow for the exit classification that occurs in grate-discharge autogenous and semiautogenous tumbling mills. An approximate treatment is given that applies for other forms of residence time distribution, provided that the mill contents are close to fully mixed.

Jan 1, 2000

By C. J. Pritchard

I commend the authors on examining an interesting method of shaft lining and attempting to improve safety in a dangerous environment by remotely installing the shaft lining. It is important, though, to not trade off shaft lining safety for long-term mine safety by lining an intake shaft with combustible material. In many operations, the mine utilities are installed next to the lining of the intake shaft, supplying a possible ignition source if damaged or overloaded. Although the polyurethane studied in the paper is of relatively high density, no mention is made of the flame retardency of the samples. When exposed to heat, small amounts of polyure¬thane will melt and bum but are extinguished when the heat source is removed. If large surface areas of combustible polyurethane - a tunnel or mine shaft - are exposed to ignition heat sources that are not removed or extinguished early, an uncontrollable, fuel rich fire may result with high carbon monoxide levels, low oxygen concentrations, and greatly increased burning rates that can have devastating effects on the ventilation system and miners' safety.

Jan 1, 1990

By William F. Riggs

In the fresh application of a frother, collector, or the change of any particular reagent, the interaction caused by this change is often overlooked since we attempt to solve a problem or improve a situation with use of a particular reagent without regard for the Interactions or side effects. When a particular reagent is added to a flotation circuit or substituted for another reagent, a series of chemical reactions occurs which. In turn, will create different physical responses. This discussion will provide a series of examples which have actually been experienced by the author.

Jan 1, 1994

By M. Taxiarchou

The continuously increasing rate of the non-renewable raw material consumption together with the production of immense volumes of solid wastes and effluents is one of the main characteristics of our modern society. This leads to an unconditional necessity to reduce the raw material and energy consumption and to recycle the used materials and products. Life Cycle Analysis (LCA) constitutes a promising tool in this direction. LCA is a methodology, whose main purpose is the objective calculation and analysis of the environmental burdens of products, processes and activities as well as the estimation of the possibilities to perform environmental improvements in combination with the rational use of raw materials and energy. The purpose of this paper is to present the life cycle of marble and granite from the quarrying to the processing stage, including the transportation between the quarry and the processing plant, by quantifying the environmental impacts that derive from each stage and the evaluation of their potential effects to the environment and to human health.

Jan 1, 2007

By William S. Butcher

Research and development of tunneling technology is rapidly taking its rightful place as an important ingredient in the Nation's research and development strategy. The state of technology in tunneling is very important to the Federal Government. Through its support, both direct and indirect, of a wide range of public works, our government, using the taxpayer's money, is the biggest buyer of tunnels. So that this money is spent wisely and efficiently, it is important that potential developments in tunneling technology that promise lower cost tunnels be pursued, if the cost of reaching the goals is commensurate with the prospective benefits. For too many years, the Federal Government's activities in the tunneling technology field were fragmented. Recently, specific coordination efforts have been initiated. It may surprise some to realize that the total Federal expenditure on excavation technology research and development, which is largely devoted to underground excavation, is growing by leaps and bounds. In fiscal year 1971 alone, approximately $19 million were expended by Federal agencies. This current fiscal year (FY 1972) that amount will increase to $24 million. It would appear that next year we will exceed the 1972 expenditure by 52 percent to bring the total FY 1973 expenditure up to $36 million. As most of this money is devoted to underground excavation, it is clear that the Federal Government

Jan 1, 1997

By William M. Clark

In 1988, the Chemical Manufacturers Association (CMA) launched Responsible Care®, a program of guiding principles created to address the publics' concern about the manufacture and use of chemicals. The Product Stewardship Management Practice code is a key component of the program. Along with the other five comple­mentary codes - Community Awareness and Emergency Response (CAER), Pollution Prevention, Employee Health and Safety, Process Safety, and Distribution - it has been initiated to protect the health and safety of member companies employees, neighbors, customers, the public and the environment. Possibly no other Management Code requires greater collec­tive effort or comprehensive commitment to implement than Product Stewardship. With its mandated cradle-to-grave control, every employee is required to consider all of the potential cir­cumstances involving product and processes, from raw material supply to customers final use or consumption of product. Degussa Corporation, a long time CMA member, fully endors­es the Responsible Care initiative and is most active in imple­menting the various codes. In fact, the guiding principles of the program are an integral part of the company's business strategy. Degussa recognizes that its long-term success and the health of each of its products, the company and the chemical industry itself, is contingent on the successful implementation of the program. Furthermore, the company believes its role in society and the economy can only be justified and sustained if it improves the overall quality of peoples' lives. Consequently, it is a dictum that Degussa products must provide a net benefit over their entire life cycle - from inception to final disposal - both in terms of their utility and their impact on health, safety and the environment.

Jan 1, 1998

By Heinz Kettling

Labor costs, which have rapidly increased in the industrial countries for several years, have forced the mining industry to develop new methods and cost saving systems. Also, because mining is basic to meeting the increasing requirements for raw materials, the mining industry is guaranteed a key position in cost cutting efforts. Although this report aims to describe major recent developments in the Federal Republic of Germany, it is restricted to a limited number of them in view of the wide variety of current innovations. The most important mining activities in West Germany are concentrated in the coal mines on the Rhine, Ruhr and Saar, in the lignite open-cast mines west of Cologne and in the potash and salt mining region in Lower Saxony and Hesse. This report will only discuss developments in the underground coal mines and the potash and salt mines, and focuses on projects of Salzgitter Maschinen and Anlagen AG (SMAG). HYDRAULIC DRILLS Drilling strata of varying strength One special difficulty faced in European coal mines is the varying of compressive strength of strata that occurs even over a few meters. The strata associated with the coal measures ranges from hard and tough sandstone or conglomerate to very soft carboniferous shale. It is often difficult to use continuous miners or roadheaders so that drifting by blasting still predominates. But the varying compressive strengths of the strata makes it difficult to choose the best method to drill the rock. For example, it is best to penetrate hard sandstone or conglomerate with heavy percussion drills. The soft carboniferous shale on the other hand, should be penetrated by high speed rotary drilling to obtain optimum performance.

Jan 1, 1979

By Sii Smith-Gruner

Blasthole drilling by todays standards is not a mature operation. In most mining appli¬cations, the blasthole drill rig is the least understood piece of machinery. Draglines, mining shovels, and haulage trucks may have more charisma, but the entire mining process starts with the drilling of blastholes to facilitate removal of the overburden and/or the primary material being mined. There are two (2) principal drilling methods them being rotary and percussion. In certain situations, percussion drilling is the most practical method, but for most applications, rotary drilling using the rotary tricone bit is the common and accepted drilling technique. While the drilling rig is on the surface and quite visible to everyone, it is really the object at the end of the drill pipe, the tricone bit, that is doing the work and drilling the hole. The rig supplies power to the bit and air to clean the hole. In addition, it must be capable of providing certain other functions and should be properly outfitted to adequately support the rotary tricone bit.

Jan 1, 1988

By W. M. Shaver, W. R. Dengler

INTRODUCTION In Canada, most of the rock being broken in underground metal mines is being carried out using traditional drilling and blasting methods. Despite advances being made in hard rock boring and other, more exotic techniques, it is Dynatec's belief that the traditional methods will continue to prevail for many years to come. It is also our belief that modest research efforts expended on the traditional methods will result in substantial financial benefits to the mining and rock tunnelling businesses. Dynatec has pursued productivity improvements through the use of long rounds in both shaft sinking and lateral development. The concept of longer rounds was developed by Dynatec on the Craig Shaft Sinking Project (RETC 1991). This paper reviews the Craig Shaft Long Round success. This technology was subsequently utilized to sink the two shafts at Aur Resources with great success. The development of a Long Round Jumbo for tunnelling is a natural progression of the long round technology developed for the Craig Shaft. RECENT HISTORY OF SHAFT SINKING Shaft sinking is one of the oldest and most difficult mining methods. Due to the relatively small amount of shaft sinking in proportion to tunnelling and

Jan 1, 1993

By Janusz Cygankiewicz, Marian Branny, Józef Wactawik

The paper presents mathematical model of concealed fire. We consider a porous medium (goaf, coal fissures) through which air flows. The set of equations is constituted by transient, two dimensional mass, momentum and energy balance equations with sources describing oxygen loss and heat generation caused by coal oxidation. Paper presents several examples illustrating the phenomenon of spontaneous heating in goaf areas behind longwall faces.

Jan 1, 1997

By Douglas J. Pendrell, Marvin D. Simmons, E. Raymond Boc

The U. S. Army Corps of Engineers is in the early stages of design for an estimated 14 m (46 ft) diameter tunnel in northeast New Jersey. This tunnel will carry flood waters from the upper end of the Pompton River in Wayne County, to an outlet in Newark Bay, a distance of 33 km (20.5 miles). The tunnel will be constructed by a tunnel boring machine (TBM), the size of which is unprecedented at the present time. The alignment is through Triassic and Jurassic sandstones, siltstones, and shales that include three beds of basalt that range in thickness from 76 to 310 m (250 to 1020 ft).

Jan 1, 1991

By R. H. T. Garnett

Offshore mining of placer diamond deposits along the coast of South Africa and Namibia has become a multi-scale activity. It is a successful offshoot of a land-based mining industry that has operated along the coastline for more than 80 years. Onshore diamond deposits have been worked by several methods from the foreshore to some kilometers inland (Hodgen). These deposits are the foundation of an ongoing industry along the coastline. The offshore diamond industry began in the late 1950s and has now come of age. Diamonds are produced along 800 km (500 miles) of coastline in water 200 m (660 ft) deep. About half of the coastline is in Namibia, north of the Orange River that defines the border with South Africa. The other half is in South Africa.

Jan 1, 1995

By James I. Mathis

Should an arbitrary reduction factor be applied to laboratory compressive strengths when designing pillars? The answer is, as is the main contention of Peng's article, probably not. Many factors affect the strength of the material remaining in the pillar. On the other hand, outside influences will influence the strength testing results from the lab. This is not the first article, nor the last, to discuss the discrepancy between the two strengths. As was discussed in the article, actual pillar strength is affected by several factors. The two mentioned were: • The scale effect of discontinuities. How large must the pillar be so that the increase in discontinuity count with size will not decrease the strength. • Non-uniform strengths and lithologic units within the pillar. The scale effect of discontinuities is important. What size block must be tested so that the rock mass strength is actually measured? For a highly fractured rock mass, or coal with a high cleat density, this sample may be quite small. Conversely, if an unaltered, moderately jointed, quartz monzonite was examined, the sample block would likely be very large. This is the subject of ongo¬ing research. More to the point, if the tested sample is sufficiently large to model the rock mass strength, then no reductions should be made in the lab strength based on this factor alone. Non-uniform strengths and variations in lithologic units will also affect the pillar strength. I am not an expert in coal mines, having gained my experience in hard rock metal mining. These problems, though, are commonplace. However, strength sampling for pillar strength determination involves sampling material from within the lithologic unit that will form the pillar, not from pieces of material found on the floor. In addition, this sampling should cover the entire range of strengths of the material in the pillar-hard units (such as the partings described by Peng), as well as soft units. Testing results should then be included in the pillar design. Contrary to statements in Peng's article, at least one rock mass rating system (Laubscher, 1990) allows for the compositing of strong and weak units into a design rock mass strength that can be used for pillar design.

Jan 1, 1993

By J. W. Leonard

Comments The venerable straight-line equation Y = Bx + A is again being rediscovered, but this time by economists, mining engineers and geologists. Two economists, William Sharpe and Harry Markowitz, from the University of Chicago and Stanford University, respectively, won the 1990 Noble Prize in economics by showing that the price of individual stocks can be related to the Dow Jones industrial average (DJIA) using the straight-line equation. According to Bill Chidester, Investment Analyst, Scientific Investment, Sharpe and Markowitz strongly emphasized the role of the beta (B) value while considering the alpha (A) value to be "pretty unimportant." Chidester claims that alpha is the "mystery" value that causes individual stocks to behave independently of popular stock-market indices, such as the DJIA. For many years, mining engineers and geologists have routinely called alpha the "nugget" or surprise element in geostatistical analyses in which a designated distance (x-axis) is related to the variance of the grade (y-axis). Because the influence of the independent variable (distance) over the dependent variable (grade variance) is ideal when alpha is equal to zero, any increase in alpha represents a loosening of influence or control within the relationship. This can be good news or bad news - good news if you are an economist sorting out off-trend stocks and bad news if you are a mining engineer trying to predict sulfur in a coal seam. With many mining trends, such as those involving the relationship of distance to the variance of grade, a mathematical relationship can be formed. In geostatistical analysis, the point where a mathematical trend ends is known as the sill. If the difference between the variance of grade at the sill and at alpha can be determined, then an estimate of the relative control for a given distance can be obtained by comparing the sill value to alpha. The extent to which alpha approaches the value of the sill provides an indication of independence or loss of trend. The alpha concept may find application with distance, time or fluid problems. The point of change can be either a change in trend or the trend limit. However, even without a clearly defined point of change or trend limit, increasing alpha values always infer loss of trend. Alpha analysis should be regarded as a valuable tool when sorting out many sets of mining data. The application of this user-friendly concept to reserves, material transport, fluid flow and other areas has been, and will continue to be, the basis of many important past and future developments in mining and geology.

Jan 1, 1996

By Albert E. Ketler

The AirBoss*200 is a unique ambient airflow sensor with important improvements in accuracy, especially in the critical low end, 0-61 m/min (0-200 fpm) where MSHA regulations apply. All solid state, its design is rugged, and there are no moving parts or delicate filaments. An on-board microprocessor calculates air velocity, linearizes and corrects for temperature, while driving voltage and current loop analog outputs to .3 meters/minute (1 ft/min) resolution. Recent developments also cover both positive and negative flow directions. A hand held computer is available to readout data and to adjust stored range selection, alarm set points, calibration data and the speed of response. Installation in hazardous areas is covered by MSHA Classes G, H and L.

Jan 1, 1993

By Jeffrey B. Smith

Introduction The gas shortage is going to be with us for some time to come. If we can set aside political and industry rhetoric (along with subjective personal opinions), we still are confronted by two serious "facts of life": (1) for almost a decade the U.S. has been con¬suming natural gas at a greater rate than we have been finding new reserves; and (2) there is a finite amount of natural gas present within the earth&apos;s crust. Much of the known and easily exploitable sources of gas (the so-called "conventional" sources, such as the high permeability sand reservoirs of the Tertiary sequence along the Gulf Coast) already have been developed; their production is declining rapidly. The total producible reserves from con¬ventional gas reservoirs amount to only 216 Tcf, less than an 11-year supply. However, several large potential resources of natural gas remain to be developed. These "uncon¬ventional sources" have low permeability and/or peculiar producing characteristics. The DOE program for development of these unconventional sources of gas is called the enhanced gas recovery (EGR) program. The primary goal of this program is to provide a data base of resource characterization and production technology that will lead to commercial development. DOE will encourage and support in¬dustry participation in developing and demonstrating technologies needed to reach this goal. Unconventional Resources Four major unconventional resources of gas have a high potential for commercial development. There are other unconventional sources (such as gas hydrates) that are too poorly defined to warrant a major development thrust at this time. The four unconventional sources of gas currently included in the EGR program are: 1. The carbonaceous shales of Devonian age in the Appalachian, Illinois, and Michigan sedimentary basins are the targets of the Eastern Gas Shales Project (EGSP). 2. The low permeability, low porosity so-called "tight" gas sandstones of the Upper Cretaceous/Lower Tertiary in the Rocky Mountain areas constitute the resource target for the Western Gas Sands Project (WGSP). 3. The free methane trapped in coal beds of both the eastern and western U. S. constitute the Methane from Coal Beds Project (MCBP). 4. The abnormally high pressured, high-temperature saltwater aquifers of the Texas¬Louisiana gulf coast are targets of the Geopressured Aquifer Project (GPAP). Basic implementation strategy for these EGR projects involve (1) assessing and characterizing the resource potential of the resource; (2) conducting cost-shared field testing with industry to improve, develop, and demonstrate various stimulation and production technologies; (3) coordinating EGR activities within DOE and with other federal agencies (such as the Bureau of Mines) to minimize duplication; and (4) aiming all projects toward commercial development of the gas resources. EGSP What type of "geological animal" is the EGSP dealing with? While gas undeniably is related to the occurrence of natural fracture systems within the shale, the overall producing mechanism and precise location of fractured, gas¬bearing locales within each basin is still poorly understood. By developing reliable resource characterization techniques and applying effective stimulation technologies we intend to elevate the Devonian shale from the status of a potential gas resource to that of a proven gas reserve. Once we have done this the private sector can take over the large-scale commercial development of the Devonian shale gas resource. WGSP The second largest project (both in terms of complexity and level of funding) is the WGSP. The primary targets for this project are the low permeability (< 1 md) gas sandstones of the Piceance, Uintah, and Greater Green River basins and the Northern Great Plains Province. Project success in these four primary geologic locales will permit investigating additional low permeability sandstones in 16 other sedimentary basins. It ap¬pears that the only practical means of increasing permeability and resultant flow rates from these sandstones lies in the use of massive hydraulic fracturing techniques. Unfortunately, it is still too early to design such jobs with predictable results. MCBP The MCBP is to be involved in producing and utilizing methane derived from coal beds. The coal, like portions of the Devonian shale, is impermeable, highly fractured (termed "cleat" by

Jan 1, 1980

By R. E. Mclaughlin, R. J. McLaughlin, A. H. Danzberger

Acid mine drainage (AMD) can occur as a natural phenome­non through oxidation of sulfide minerals. Oxidation by air and water can be exacerbated by mining. Because AMD can exhib­it low pH, it is capable of extracting heavy metals from mineral deposits. The result is highly acidic drainage with elevated heavy metal concentrations - the combination of which can cause extensive environmental damage. Because of the importance of these factors, this paper is focused on sulfate based AMD. Due to widespread mining, the occurrence of AMD is ubiqui­tous. As a result, several approaches to treatment have been developed. Chemical treatment using alkali is most commonly employed to treat AMD. There are alternative methods of treat­ment, as well as alternative ways of handling treatment sludges or concentrates. Dewatering of sludge or concentrates is beyond the scope of this paper. Within the family of chemical treatment processes, there are three principal recognized methods, namely, "Conventional," "High Density Sludge" (HDS) and "Heavy Metals Removal Process" (HMRP). All three are now employed or specified for treating AMO at mining sites which are being reclaimed under Superfund. Only limited data are available for more specialized chemical treatment processes such as "ferrate", borohydride membrane and electrochemical methods. Therefore, these data are not included here. Performance data for these three processes are presented in this paper and comparison among them is made. Comparisons include consideration of water quality, sludge characteristics, and operational ease. Capital and operational cost comparisons of these processes were addressed in a previous paper by the authors (see bibliography). The results presented here are impo1tant not only to metals mining, but are also applicable to other industries experiencing metals-laden acidic wastes including: coal mining and prepara­tion, metal plating, and electronics circuit board manufacturing. The acceptance of any process should be based on bench scale demonstration before implementation is contemplated. The three processes included herein are discussed in relation to the particular sites at which they are in use, or their use is planned. The sites selected were representative of the various types of processes and the wastewater parameters.

Jan 1, 1998