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By Ivor Hawkes, Malcolm Mellor

INTRODUCTION There are currently around fifteen companies in the United States and Europe manufacturing hard rock tunneling machines. In recent years upwards of 200 hard rock tunnels of lengths up to 12 miles and diameters to the order of 30 ft have and are being successfully driven by over 100 different machines. It has been predicted that within the next decade over 2,000 miles of tunnels will be driven for transportation purposes in the United States alone (OECD Advisory Conference on Tunneling, Washington, 1970) and it is expected that eventually most tunnels including mine drivages will be excavated by machines. All tunneling machines have certain common basic functions; thrust is applied to drive or hold the rock cutting tools into the face, and torque is applied to rotate the cutting tools over the face so that they can continuously break out rock. The speed of head rotation, together with the torque requirement, determines the cutter head power. (The power required to push the head forward is usually negligible.) There are many factors which determine how successfully a given tunneling machine will perform in a given rock but one of the most important is effective utilization of cutter head power. This paper is a review of the specifications and performance of hard rock tunneling machines, obtained from manufacturers' catalogs, published literature, talks with manufacturers and visits to operating machines throughout the United States and Europe.

Jan 1, 1997

By J. F. Dresser

Managing environmental compliance at a complex facility has the potential to bring a high degree of personal and professional satisfaction to both the corporation and the individuals responsible for day-to-day operations. The decade of the 1990's, however, has seen the emergence of a nationwide trend of aggressive federal and state civil and criminal enforcement for environmental violations. This trend, spearheaded by the U.S. Department of Justice (DOJ) and the U.S. Environmental Protection Agency's (EPA) Office of Enforcement, has the potential to place the corporation, its corporate officers, and compliance personnel at collective professional risk, as well as a growing tendency to place accountability on individuals. Management of environmental compliance has been anecdotally compared to a shooting gallery at a carnival, with the following exception: At the shooting gallery, successfully hitting nine out of ten targets usually brings a reward and recognition of shooting skill; hitting nine out of ten environmental compliance expectations not only brings agency consternation and negative publicity, but the "gallery" will likely shoot back with stiff fines and possible criminal allegations. Faced with the challenges of the new environmental compliance shooting gallery, corporations and professionals are often left asking themselves, "How do we (or more appropriately, can we) win at this game?" This paper examines recent federal enforcement statistics and offers several suggestions for coping with the responsibility of managing environmental compliance in the 1990's.

Jan 1, 1992

By A. A. Mathews

INTRODUCTION When Palmer King asked me to prepare a paper for this conference, it seemed quite appropriate, since I am Chairman of Subcommittee No. 4 of the U. S. National Committee on Tunneling Technology and we are presently making a detailed study of contracting practices. Before the end of this year, we expect to publish our report containing guidelines aimed at improving our contracting practices and minimizing the problems which develop therefrom. The American construction and mining industries today are glowing examples of the ingenuity of man pitting his wits against the unknown. Without the promise of rewards commensurate with the perils faced and the effort expended, it is doubtful that these industries could have reached their present state of advancement. Nevertheless, these industries are still primitive compared to many others such as aerospace and electronics. That our present contracting practices leave something to be desired is evidenced by the fact that many of our underground projects wind up with tremendous increases in estimated cost, financial disaster, and costly dispute and litigation. The situation is aggravated by the current economic uncertainty, energy crisis, and shortage of materials. At the same time, if our industries are to develop their maximum technologic potential, we must employ contracting practices which will encourage that development. Most of the contractual problems related to underground construction are associated with risk and its management. Unless all of the ramifications of this subject are understood, it will be difficult

Jan 1, 1974

By Harold G. Arthur

INTRODUCTION Stillwater Tunnel construction is scheduled to start in the spring of 1973. The tunnel will be the site of an extensive program in rapid excavation research. This paper presents a progress report regarding our plans and relates the tentative decisions which have been made on how to carry out the research effort. The details are subject to revision as more input is obtained from other Government agencies interested in tunnel construction and from experts in industry and educational institutions. The objective of the research program is to bring about faster, less costly tunnel construction. This objective will be pursued through the development, improvement, and evaluation of various construction systems and investigative techniques. The need for this kind of program was recognized by the National Research Council, in its authoritative report "Rapid Excavation - Significance, Needs, Opportunities." (1) The Council advocated a federally funded $200 million, 10-year program to help meet the $69 billion market it expects in underground excavation between 1970 and 1990. The significance of tunnel construction to Reclamation is made clear by statistics of its tunneling experience and outlook. Reclamation has constructed 174 water conveyance tunnels totaling over 190 miles, Six tunnels are presently under construction which have a combined length of about 27 miles. There are on the books nine authorized, but unfunded tunnel projects totaling another 70 miles in length. Many more miles of tunnels are included in programs in various stages of investigation.

Jan 1, 1997

By B. L. Gibbs

Computers have been used in the minerals industry for about 30 years and, in a few cases, longer. With the explosion of microcomputing during the past 10 years, computers have changed how many minerals producers go about their work. What computer usage trends are active in the minerals industry today, and what can we expect in the future? In general, computer usage is accelerating. Engineers and geologists are becoming increasingly "application literate." Soft¬ware is increasingly oriented to how people work. User interfaces have improved, so most users need to know only a mini¬mum of system commands and structure to work with a computer. Most industry professionals know how to use word processing and spreadsheet pro¬grams. AutoCAD appears to be the drawing program of choice. One reason is availability of training and add-on programs for earthwork, mapping, contouring, etc. Another frequently cited reason for using CAD is the ability to quickly make changes to a map or design, as compared to hand methods. Management is moving toward greater acceptance of computer usage. Computers do not need workman's compensation ... even though they may get sick and take a few days off! Computer hardware used in most minerals-producing companies is strongly personal-computer based and likely to remain so. The 486 personal computers are inexpensive as compared to workstations and provide the power and speed to run most applications in minerals industry engineering offices.

Jan 1, 1994

By John C. Cook

In reasonably dry rock, long-wave radar can theoretically explore to distances approaching 75 meters (250 ft). High-resolution radar reflections have already been demonstrated through 13 m of hard limestone, through 9 to 18 m of coal in place and through 225 m of rock salt, using only low-power experimental radar equipment. Radar reflections have been received through the rock from rough pillar walls, from faults, and from a slim, uncased, vertical drill hole. In three years of intermittent experimentation, the feasibility of rapid radar exploration of large volumes of rock, with portable equipment, in deep, wet workings has been demonstrated. With future, improved equipment the theoretical working range, of the order of 75m, is expected to be attained in most hard rocks. THE TECHNIQUE Fig. 1 illustrates an early "monocycle" radar system (1) set up in a coal mine. This radar equipment is entirely different from that employed for detecting distant objects through the atmosphere. However, the basic principle is the same: a pulse of electromagnetic energy is radiated by the transmitter, a portion is reflected by some "target" object embedded in the surrounding medium and some of this energy is collected by the receiving antenna. In the receiver, the pulse is amplified, is "stretched out in time" by a sampling process, and is displayed on the screen of a cathode-ray oscilloscope. It may also be recorded on paper or magnetic tape. Fig. 2 illustrates a

Jan 1, 1997

By Max John

INTRODUCTION One of the main advantages of the New Austrian Tunneling Method (NATM) is its adaptability to varying rock conditions. This method is therefore successfully applied when complex geologic features are expected which cause uncertainties in the prognosis of the rock mass behaviour, as was the care at the Arlberg Expressway Tunnel. Furthermore, by employing the NATM problems are avoided when encountering varying geologic conditions or even extension fault zones along the tunnel, as was the case at the Dalaaser Tunnel and Perjen Tunnel. The NATM can also be used for rock and soil. The following examples will show how various rock conditions can be mastered. In accordance with the NATM all tunnels which will be discussed are road tunnels having a cross section area between 70 and 100 m2. The construction consists of a primary support, which ensures stress redistribution during excavation (Figure 1). The primary support is reinforced shotcrete strengthened by steel arches, when necessary, and rock bolts. When encountering rock pressure, swelling rock or soil, the primary support is suplemented by an invert arch. The purpose of the secondary lining is to increase the safety of the tunnel with regard to long-term stress redistribution processes or changes in rock mass properties as well as to protect the insulation. The secondary lining consists of cast concrete without reinforcement and is generally 0.25 or 0.30 m thick.

Jan 1, 1981

By Dietrich F. C. Hudewentz, Alfred H. F. Lücker

For centuries tunnellers have made use of the experience of miners. In West German coalmining tunnellers have returned the impulses in recent years by giving the miners valuable stimuli with the result that a technology has evolved which benefits drill and blast heading, opens the door to TBM heading and has developed special measures for difficult strata conditions in deep coal mines. WHAT DO THESE ROCK HEADINGS LOOK LIKE? The main roadways dealt with in this paper have crosssections of 20 to 40 m2, big enough to allow the massive airflows needed to aircondition the mines. Because of the difficult strata conditions they have to be supported: in shotfired headings mainly with multi-element arches, in TBM headings with rings of 6 to 6.5 m diameter. In West German coalmining the majority of rock headings are blasted. The proportion of rock headings driven by TBM was 11 % in 1980 and 16 % in 1981, a rising trend expected to continue. Drill and blast headings Drill and blast headings are normally equipped with two or three-boom electro-hydraulic jumbos, electro-hydraulic crawler-mounted loaders with 1.2 m3 shovel capacity, a movable working platform and both chain and belt conveyors for dirt clearance to the minecar loading point. Fans and air-condition plant complete the equipment. Spacing between arches is usually 0.8 m. Investment for this type of mechanisation works out at around 1.3 m DM.

Jan 1, 1983

By D. Constantinides

In 1981 a Zn-Ag-Pb deposit was discovered in the vicinity of Molai, Greece. Subsequently, it was determined to be of the Kuroko type. The geology of various areas in the southeast Peloponnesean Peninsula is similar to that of the Molai deposit. Since favorable geologic criteria are present, absent, or unknown in varying degrees in all areas, it was deemed necessary to classify and rank the prospective areas according to the level of information available. For each level of information, an ore discovery model based on pragmatic exploration criteria was developed, enabling the favorability of occurrence to be calculated for each area. A Monte Carlo simulation was used to calculate the probabilities, the input data consisting of quantitative and qualitative estimates of the geologic criteria for each area. Three levels of information were modeled : Level A consisted of 9 criteria, level B of 12 criteria, and level C of 20 criteria. The three levels of information were tested on the Molai area. The results exceeded expectations, showing the gen¬eral trends which control mineralization at the lowest level of information. With an increase in the level of information, geological trends become more evident and a differentiation can be made between areas containing Cu mineralization, exhibiting a low probability, and areas likely to contain Zn-Ag-Pb mineralization. The models were then applied to the neighboring areas - only level A and B were available.

Jan 1, 1986

By Ryota Kasahara

In 1981, a gas outburst accident occurred in the Yubari Shintanko coal mine, the only expectant mine in Japan, it caused 93 deaths. As a result, Yubari Shintanko closed in 1982. This major disaster was a turning point for sustainability of Yubari City, the largest coalfield in Japan. Finally, Yubari City was bankrupted in 2007. This paper aims to explore how miner’s children experienced this disaster and felt about region, family, and themselves, and to explain the relation between region declining and children’s lives. The data of this paper are the archived 600 essays, written by the junior high school students at the time of the disaster. There are three findings. First, the children who lost their father were the most shocked. They faced profound sadness. But they expressed that they had decided to overcome their sadness with surviving family. Second, the children who didn’t lose their father were also influenced. They were anxious about the future of Yubari, their family, and themselves. Furthermore, they decided to strive for their future. Third, they understood the disaster as a turning point of Yubari declining and looked ahead their future outside of Yubari. In conclusion, this disaster created their hopelessness to Yubari region and, as a result, promoted the decline of the city through their migration to other city. Furthermore, it is important to clarify that Yubari City has to continue the struggle to the regeneration.

Jan 1, 2017

By Fredrick C. Kruger

We can confidently predict such obvious long-term trends affecting the minerals industry as - increasing consumption, exhaustion of easily discovered near-surface ores, and sharp limitations upon open pit mining by environmental considerations. There- fore, we must intensify the exploration for, and the development and exploitation of, deep bodies of potash and other ores. This paper examines the state of the art of the search for, and the evaluation of, potash from both a geological bias and a mining practicability. The use of indirect geological methods and geophysical techniques, followed by expensive deep drilling, are the conventional approach to evaluation and development of mining plans. The geologist and the geophysicist will have to find ways to perform both of these tasks better and cheaper.

Jan 1, 1973

By R. C. Bunge

Many minerals float best with fatty acids in the intermediate pH range. For example, fluorite, a semi soluble salt mineral, exhibits a maximum contact angle and a maximum flotation recovery in the pH range of 6-8 after conditioning in a palmitate solution (fig. 1). The maximum in flotation coincides roughly, as many researchers have observed, with the boundary of bulk precipitation of the fatty acid. According to fig. Z this boundary is in the above case of 5xl0-7 M palmitate approximately at pH 6.3. For assessing the phenomena occurring at the bulk precipitation boundary of fatty acids, the surface tensions of carboxylate solutions have been measured under various conditions. Fig. 3 shows the surface tension development of palmitate and myristate solutions of increasing concentration at pH 12. Also shown are the bulk precipitation edges (BPE) of the respective solid species that is stable under these conditions, that is the potassium acid soap, HKAZ. Both curves display a similar behavior. As the concentration of carboxylat,e increases, the surface tension decreases, until a minimum is reached at which the curves level off. The decrease of surface tension with increasing carboxylate concentration is generally taken to indicate the surface excess of the carboxylate ion. The point where the curve suddenly levels off has not yet been explained. While it is well known that the onset of micellization (CMC) may cause such an inflexion of the surface tension curve, this cannot be the case here because the position of this point depends, as shown in fig. 4 for palmitate, on pH (the CMC is generally independent of pH). We believe that this point indicates the precipitation of a colloidal acid soap (colloidal precipitation edge, CPE) before the bulk precipitation of this species sets in (BPE).

Jan 1, 1994

By J. P. A. Hortley

In conventional electrolytic copper production, looped copper starter sheets, on which the copper is deposited, are supported by hard-drawn copper bars. These bars have cross-sectional areas of between 1 and 1.4 in2. The suspension bars serve two purposes: firstly to support the cathode, which can weigh up to 150 kg, and secondly to introduce the electric current. IYI examined these two requirements in detail to see whether a better design could be achieved. Considering firstly the current carrying requirement, it wee noted that under normal refinery conditions, each cathode carries between 400 and soak. If one applies the generally accepted rule that 1 in of copper can carry 1000A4 a suspension bar need theoretically contain only 1/2 in2 of copper. This contention is supported by the fact that the 500A current passed through the cathode also appears to pass quite satisfactorily through the two support loops, which have a cross-sectional area of approximately 0.35 in 2. Turning now to the strength requirements, the cross-section of hard-drawn copper bar required to support a 150 kg cathode is relatively small, and easily met by the present designs. It is not, however, the static load applied by the 150 kg cathode immersed in the electrolyte which causes the damage to the hard-drawn copper, or even the increased static load of a 100 kg man standing on one foot in the centre of the bar; the damage is actually caused by the dynamic loads applied to the bare when they are dropped, thrown into containers, lowered too rapidly into the cell, or otherwise mistreated. The important requirement is therefore that the bar does not permanently bend. Its proof stress of limit of proportionality, rather than the amount that it deflects under static loading, should be the strength criterion. With the hard-drawn copper normally used for the manufacture of suspension bars, it has been observed that the copper becomes annealed during use, particularly at the end of the bar where the current is introduced. Thus, after a relatively short time, the cathodes are in effect being supported by annealed copper bars.

Jan 1, 1978

By Jack Barrett

The oxidants which participate in the bacterially catalyzed oxidation of minerals are dissolved oxygen and some aqueous iron(III) complexes. Speciation studies indicate that these complexes consist of iron (III) -sulfate and iron (III) -arsenate ions. The complexes have different oxidizing powers as indicated by their calculated standard reduction potentials. The thermodynamics of the oxidations of pyrite and arsenopyrite are related to the mechanisms of the reactions. The mechanisms are discussed in terms of primary processes occurring on the mineral surfaces and the secondary reactions of the primary products. The importance of the conclusions to plant operation is discussed.

Jan 1, 1993

By John A. Organiscak

The Bureau of Mines evaluated a new dust control technique for longwall personnel required to work at the tailgate end of the face. This technique utilizes a water-powered scrubber to clean a portion of the face air, which is discharged behind a brattice partition at the working area. Laboratory simulation of this system in a wind tunnel resulted in average efficiencies greater than 70 pct with system efficiency directly related to scrubber quantity. Underground evaluations indicated a similar direct relationship between scrubber quantity and system efficiency. Gravimetric measurements of respirable dust made during these underground evaluations resulted in average protection efficiencies ranging from 30.7 to 42.5 pct with increasing scrubber air quantity.

Jan 1, 1983

By Robin G. Adams

The market prices received by producers of internationally traded commodity metals have been, and continue to be remarkably volatile and unpredictable compared with most other traded goods and services. This volatility results in an erratic financial performance on the part of producing companies, disruptive and often inflationary cost changes for consumers, unreliable tax revenues and export earnings for host governments and severe social and economic pressures on local, sometimes remote, communities which are dependent on the activity in question. Generally speaking, price volatility appears to be associated with the inability of the metal producing side of the industry to regulate the volume of supply in a manner that is consistent with metal demand, which in turn reflects broad macroeconomic and industrial developments around the world. This statement does not purport to apply to all metals or to all instances of volatility of course. Price movements may occur as a result of pure speculation or even illegal manipulation of the commodity markets. Embargoes, boycotts and other politically induced supply changes may contribute. Threatened or actual strikes also cause artificial swings in sales volumes and prices. How- ever, most of these developments are of a short-term nature. Yet metals price cycles may last for several years, as demonstrated by the extended copper price trough from 1981 to 1986. This paper deals with price volatility which reflects long-term economic cycles and the adaptive processes that exist within the industry in response to such cycles. Special emphasis is placed on the role of forecasts and forecasters in these processes. It should be said at the outset that this reflects the personal experience of one forecaster working in private sector commercial consulting practices that are independent of producers, consumers and host governments. However, the experience does cover the entire period since 1973 and has involved working with a substantial majority of the major companies that supply high volume commodity metals. By way of background it should be stated that the post-1973 world economy has provided a challenging environment for forecasters. One cannot be precise about the forecasting record of either industry insiders or outside consultants, financial analysts and academic forecasters because comprehensive records have not been kept, or if they have the results are too embarrassing to be published. Institutions such as the World Bank have published forecasts of the prices of major commodities on a regular basis and these have, presumably, had some influence on financing decisions in the industry. This record along with our own experience and numerous discussions with metal producers, major consumers and host governments permits certain generalizations to be made. The most important of these is that during the early 1980s. from about 1980 through 1985/6, the forecasters system- atically and substantially over- estimated metal prices. While some fore- casters did correctly anticipate a recession in the early 1980s and some consequential decline in prices, the magnitude and duration of the decline was far greater than anyone foresaw. This systematic forecasting "failure" appears to have occurred independently of the forecasting methodology employed. Moreover, its extent cannot be explained by obvious factors such as incorrect macroeconomic assumptions. There appears to have been some kind of structural change in the world mining and metals industry over this period

Jan 1, 1989

By Alan D. Hoagland

The Flat Gap Mine is on Copper Ridge in the Appalachian Valley of East Tennessee, Large zinc orebodies occupy zones of solution and collapse breccias in lower Ordovician Kingsport limestone and dolomite, The principal ore mineral is sphalerite and the principal gangue is dolomite, The orebearing horizons are considerably more than 95% covered by thick residual clay, and geochemical prospecting under these conditions is an effective exploration technique which played an important role in the discovery and exploration of the Flat Gap Mine, The residual nature of the over-burden at Flat Gap is emphasized, Background heavy metals (mainly zinc) range from 50 to 200 ppm, and the anomalies range to 3000 ppm and more, About 80% to 9W0 of the soil zinc is in relatively insoluble form in solid solution with the hydrous iron oxides and in the crystal lattice of the clay minerals. Quite discrete zones in the soil with sharply contrasting metal value boundaries mark vestiges of bedrock mineralization, and such anomalous soil areas are often contiguous with partially weathered ore. It has not been possible on the basis of chemical criteria to distinguish between an anomaly formed from non-commercial mineralization and one formed from ore.

Jan 1, 1962

By S. C. Sun

The grinding of coals for coal preparation has been studied extensively by previous investigators, but no similar work has been done on coal lithotypes (l-4). However, the different natural breakage characteristics of coal lithotypes have been recognized and utilized by the coal industry (5,6) to develop the Longway Burstlein process (7) for the concentration of macerals(8). The specific objective of this research was to determine the relative grindability of lithotypes, obtained from both anthracite and bituminous coals. An attempt was made to relate the findings, wherever possible, to the chemical and physical properties of the tested lithotypes. Another aspect of this research was to ascertain the size distribution and grindability of lithotypes ground at a various number of revolutions in a Hardgrove mill.

Jan 1, 1970

By William W. Kephart

Brockway Glass Company, Inc., manufactures glass containers at fourteen plants located in nine states. The relatively high place value of the major glass batch components dictates that raw material supplies be obtained from numerous sources in the United States and Canada. One objective of our central composition control program is to arrive at a glass composition with similar physical properties at each of our plant locations. This requires that adjustments be made in the batch compositions to compensate for chemical variations from one raw material source to another. Minor chemical variations will occur in sand, limestone, and dolomite from one source to another. Major variations are present in the alumina sources because of the diverse rock types utilized.

Jan 1, 1973

By William J. Orlandi

The intent and scope of this paper is to present to you, as concisely as possible, the problems and requirements -- and what we consider advantages -- of all-belt haulage in a modern underground coal mine. Mine No, 10, at Pawnee, Illinois, was opened in 1951; consequently, all the planning and consideration given to haulage selection was based on information then available and on Peabody Coal Company? s experience to that date,

Jan 1, 1961