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By Alan E. Isaacson

Extensive gravel deposits exist within a six-county area in the mountains surrounding the Salt Lake Valley, and in the mountain ranges to the west. The six-county area includes Davis, Salt Lake, Summit, Tooele, Utah, and Wasatch Counties. The majority of these are beach deposits from prehistoric Lake Bonneville. However, real estate development associated with a projected population increase of 54 percent over the next 20 years is expected to remove most gravel deposits in Salt Lake County from consideration for mining, forcing gravel operations to relocate from eastern Salt Lake Valley to the Oquirrh and Stansbury Mountains farther west. The gravels in these ranges are of lower quality and require additional processing to manufacture asphalt and concrete. Replacing gravel resources along the Wasatch Front with resources in the Oquirrh and Stansbury Mountains over the next 20 years has the potential to increase construction costs by nearly $1 billion. The majority of this cost (82 percent) is the result of increased transportation costs due to longer distances to market. The remainder of the cost is attributable to lower quality gravels that will require additional processing in the manufacture of asphalt and concrete. The following analysis and discussion does not take into consideration the amount of crushed stone that is currently being used in the construction industry in northern Utah, its use as a substitute for lower quality gravels, or as a factor in the base case projection.

Jan 1, 2001

By H. S. Chang

A three-dimension two-phase (air and dust) computer model was developed to model air velocity and respirable dust distributions in the longwall faces. This paper describes the derivation of the model including the model features, mathematical equations and boundary conditions. Example simulations were also performed for two longwall faces where measured respirable dust and air velocity distributions were available. The results indicated the model can simulate the mine conditions fairly accurately.

Jan 1, 1996

By E. F. Divers

In response to a request from the Mine Safety and Health Administration, the Bureau of Mines has recently completed a respirable dust survey of 18 U.S. coal preparation plants. Of these, three were essentially free of dust problems. Respirable dust exposure of workers in the remaining plants depended on the time spent in the dusty areas. In five of the plants surveyed, Bureau tests showed that in some areas worker exposures could exceed Federal dust limits in less than 2 hours.

Jan 1, 1988

By Ahmet Gursoy

Maryland, will be the widest vehicular tunnel ever built by the trench tube method. Careful coordination and planning were required to meet the tight and fast design and construction schedules. During the preliminary design, traditional design drawings were bypassed in favor of 25 preliminary design reports representing major work breakdown structures (tasks). For each task, alternative design solutions were examined and analyzed by means of trade-off studies on the basis of engineering, constructibility, and economic considerations, thus providing an overall conceptual value engineering approach for the entire project. So far, total value engineering proposed by the contractor for Contract I I (largest contract of the project at $245 million) is less than 1.5 percent of the contract value. This is an important indication of the success of the design phase planning.

Jan 1, 1983

By Maria S. Adusumilli, A. Bhaskara Rao

ABSTRACT The presence of gold in lateritic crusts over mafic and ultramafic volcanogenic complexes in / and greenstohe belts, has called the attention in several parts of Brazil and also in Australia. Recent studies reveal the variety of structures and mineralogy of such crusts, and their importance in correlation with host(bed) rock types, as exploration guides, specially for greenstone belt metallogeny. The expected nature of growth of plates and/or nuggets in such crusts is under detailed study, and is considered as possibly due to dissolution and reprecipitation phenomenae of disseminated-fine-low grade ore in the host rock, in this investigation, laterite geochemistry, though incipiently discussed todate, is of fundamental importance and significance. Lateritic gold can be classified texturally as: dusty and diffused, fine, thin platy, taDular, and nuggets. Such gold is pure, and is often restricted to nodular (pisoliths, ooliths, concretions) forms or the matrix, that constitute the crusts or lateritised gravel beds which have an essentially goetnitic nature. Further this gold is recovered directly by mining the crusts or the adjoining placers with the metal derived from them. The thickness and extension of laterite crust zones is extremely variable depending oh the paleoclimatic conditions, and is conditioned to the favourable lithology and its structural expression. However, the "growth" of gold in these laterites will be conductive , without doubt, to several small scale mining activities, specially in the developing countries and regions limited to latitudes 309N and 309S.

Jan 1, 1987

By David A. Roberts, Edward J. Cording, James W. Mahar, Robert A. Robinson, Noppadol Phienweja, Harvey W. Parker

Horizontal inclinometer and deflectometer casings were used to measure deformations up to 15.2 m (50 ft) ahead of and adjacent to the heading in highly fractured and sheared shales at the Stillwater Tunnel. The measurements were compared with borehole extensometer and tape extensometer deformations to evaluate ground movements in advance of, adjacent to, and behind an advancing tunnel heading. Ground deformations of up to 127 mm (5 in.) occurred during passage of the innovative "walking blade-gripper" TBM. Deformations were compared with curvometer/distometer and vibrating wire strain gage data from steel ribs to assess rock-support interaction.

Jan 1, 1985

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 N. E. Green, W. E. Bennett, G. P. Harrison

INTRODUCTION The art of raise boring has seen rapid development and use in underground mines both for primary development and production during the past 10 years. The intensive full scale tests by a major mining company in the Precambrian rocks of the Sudbury district of Ontario, Canada, have lead the way to the general acceptance of the raise drills. The rock successfully raise bored in the Sudbury area has compressive strengths varying from 30,000 to 50,000 p.s.i. As a result of the intensive study, it became evident to many mining companies that raise boring could be adapted to many mining systems. Many companies have modified their planned mining methods to incorporate raise boring. The result has been a more rapid development of their mine and naturally, an economic advantage to them. In conjunction with the acceptance of the raise drills, the range of equipment has broadened in terms of size, capability and efficiency. The concept of raise drilling and the general arrangement of the equipment has seen little change. At some locations there have been reported successes of drilling pilot holes up

Jan 1, 1997

By Walter Keune

Object Modeling Technique. This formal descriptive language makes it possible to formulate requirements in the real world in such a way that they can be implemented in the form of entities (cf. Entity Relationship Model[Che83]) and methods (see Figure 1). The object {Roadway} is graphically depicted by means of the Polygon method.

Jan 1, 1996

By Ian Longson, Darron W. Dixon

This paper describes the results of an investigation into the application of a statistical method for the prediction of general air-body methane concentration in longwall coal districts. An important and necessary part of the research was the acquisition of representative monitored mine environmental and coal production data. The monitored data was used to build time series models of general air body methane concentration, air velocity, barometric pressure, coal production and methane drainage variables of differing timescales according to the Box-Jenkins method of time series analysis. The univariate models were used to identify causal relationships between methane concentration and its explanatory variables. Coal production was found to be the dominant variable in the determination of the quantity of methane emitted and where appropriate, multivariate time series models were built in which expressions for methane concentration in terms of coal production were obtained. Finally, forecasts of methane concentration values were generated from the multivariate models to determine their forecasting capabilities.

Jan 1, 1993

By S. M. Khandrika

It is shown that dewatering of fine coal particles (D50 : 21 microns) is enhanced near the point of zero charge. The coal surface is modified by the addition of copper ions and adjusting pH to precipitate surface active metal hydroxy species which promote agglomeration and produce low moisture cakes. Filtration kinetics data are used in calculating filter cake parameters from an integrated form of Darcy's law. The influence of copper ions and pH on filter cake parameters and correlations among them are presented.

Jan 1, 1993

By Joseph M. Tarantino, Eric F. Perry, Keith B. C. Brady, Michael W. Smith

The Pennsylvania Department of Environmental Protection in 1998 reviewed its permitting process to determine how effective its program has been in preventing pollution and to identify here it could be improved. Of the 1,699 bituminous mine permits issued from 1987 to 1 996, 50 were identified to have current or past postmining discharges with water quality problems. The remaining 1,649 sites had no known current or past postmining discharges problems. The 50 sites were selected for further review. On closer examination, 33 of these permits no longer had water quality problems or the problem had not actually resulted from the permitted mining activity. Only 17 permits, or one percent of the total permits issued, were found to have caused long-term postmining discharges serious enough to require treatment and prevent bond release. Analysis of these 17 sites using current knowledge of mine drainage prediction, revealed that the most common cause of error was inadequate information in the permit application. Errors in interpretation of the application data and in implementing the permit were less common. A very small percentage of all permits issued resulted in postmining discharges for no clearly identifiable reason. Trends over the 10-year study period indicated a decreasing incidence of permits resulting in postmining discharges. Further, with the exception of the first few years of data, most of the postmining discharges were of mildly acidic or alkaline quality and amenable to passive treatment.

Jan 1, 2000

By M. H. Pelkki, R. J. Sweigard, P. W. Conrad, J. M. Ringe, D. H. Graves

Research has shown that excessive soil compaction is detrimental to the establishment of trees in reclaimed soils. Dry bulk density and penetration resistance are two soil parameters that can be used to indicate the level of compaction in reclaimed soils. It is believed that reclamation practices that minimize soil compaction will produce better results when forestland is the intended postmining use. The University of Kentucky has developed reforestation test cells on reclaimed soils at a surface mine in eastern Kentucky to test this hypothesis. Each test cell has been planted with various species of trees. Since 1997, data have been collected at these test cells for soil average dry bulk density, average penetration resistance, average depth to refusal and average survival rate of trees. These data have been correlated to determine the relationship between soil compaction and tree-survival rate. It is believed that these two soil-compaction parameters may ultimately be used to predict tree-survival rates on reclaimed surface mined lands.

Jan 1, 2003

By Brian H. Jasperse, Nicholson Peter J.

Gravity retaining walls have been constructed using Deep and Shallow Soil Mixing (DSM and SSM) since 1991 in the United States. These walls, for both temporary and permanent uses, were constructed by mixing cement with in-situ soils over a volume containing 100% of the required gravity wall zone. Modern design techniques have reduced costs substantially by forming the required gravity wall section as a composite mass. Using ratios of 15-35% by volume, treatment f the ground forming the required gravity section has reduced the cost from about $40 to about $20 per square foot. Design, construction and actual performance of these gravity walls are presented.

Jan 1, 1999

By William F. Hahn

It is a pleasure to speak to this group about special crusher installations which are in the bauxite and phosphate rock processing industries. The installations to be discussed demonstrate the variety of conditions, materials, and results desired which must be evaluated before a selection is made from the specialized crusher technology available today. Those of you who are closely involved with phosphate rock and phosphate products processing will find some of this information a bit interesting and perhaps alien to your own descriptions or every day references. It is given from a "crusher" manufacturer's viewpoint and therefore is infused With our flair and language. General features of six (6) different crushers will be shown in cross-section With slides and will be discussed in the same order.

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 Bruce A. McKinstry

For many major mining projects the time frame from initial planning to production can be measured in terms of decades. Hecla's Silver Shaft project, which is scheduled to go into production by the end of this year and includes a complete surface facility, shaft with an ultimate depth of 2,348 meters (7,700 feet), complete ore pass and loading pocket system, and 610 meters (2,000 feet) of development drifting and stope preparation, was initially concieved in the Fall of 1979. This duration of a mere four years from conceptual engineering to production is a testimonial to what can be accomplished when a progressive mining company and an innovative contractor work together as a team rather than developing into two warring camps as often happens.

Jan 1, 1983

By Richard R. Klimpel

This paper reviews the use of sulfide mineral collectors in industrial flotation practice. The approach of the paper is to characterize sulfide mineral collectors in a number of ways, including by chemical structure, by influences with different classes of mineralogy, by interactions with particle size, and by interactions with frother type.

Jan 1, 1999

By F. Kennedy

Consolidation Coal Co. (Consol) supports an active research and development effort to improve the safe, productive mining of coal and to use coal in an environmentally acceptable manner: Attention will be focused on degasification of coal seams, continuous coal transport systems, earth sciences activities, and coal combustion. Brief mention will be made regarding the SO2 emissions control programs. The research program constitutes about 1 % of Consol coal sales, which positions Consol as the preeminent coal company supporting broad-based research addressing the full spectrum of the various problems associated with using the nation's abundant reserves of economical, readily available fuel.

Jan 1, 1990

By Robert A. Robinson, Steven R. Thompson, Harvey W. Parker

The Mt. Baker Ridge Tunnel, under construction in Seattle, will be the world's largest-diameter soil tunnel with an inside diameter of 19.2 m (63 ft) and an effective outside diameter of about 24.4 m (80 ft). The five-lane highway tunnel will be constructed using a "stacked-drift" scheme in which an articulated or "flexible" tunnel lining consisting of 24 concrete-filled drifts is constructed to form a horizontal compression ring followed by removal of the soil core. Geotechnical factors, including variable strength hard fissured soils, high horizontal stresses, potentially unstable sands, and prior slope instabilities, significantly influenced the innovative design and construction approach.

Jan 1, 1983