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By M. Superfesky, P. Michael

Introduction The US Office of Surface Mining (OSM) is proposing changes to the Code of Federal Regulations in the interest of minimizing the adverse effects of excess-spoil-fill construction on the “prevailing hydrologic balance, fish, wildlife and other environmental values” (70 FR 35112). The proposed changes will require: (1) minimization the amount of excess spoil generated at a mine site; (2) minimization of the size of the fills constructed; (3) consideration of alternative configurations for disposal; and (4) development of a disposal plan that would minimize adverse impacts to the environment.1 To achieve those objectives, mining companies operating in steep-sloped Appalachia will likely build excess spoil fills (also called valley fills) that toe out at higher elevations in the hollows (i.e. to prevent or limit burial of streams). Consequently, the slopes of fill foundations will generally be steeper. Whereas the authors of this paper support these measures to protect the hydrologic balance and general environment, we wish to point out that placement of fills on steeper foundations can negatively impact the stability of the fills if proper care is not taken during their construction. It is important to note that in addition to impairing human safety, valley fill instability can negatively impact streams, the riparian habitat etc., and thus defeat the very purpose of the spoil minimization measures proposed. We do not, however, propose additional regulatory requirements pertaining to valley fill stability. Rather, we intend to emphasize the importance of engineering requirements already on the books, especially as they apply to the predominant type of valley fill constructed: the durable rock fill. We believe that the practice of restricting valley fills, to higher elevations in the watershed leaves less room for error in the design and construction of stable structures. This paper gives a quick review of the nature of excess spoil generation; methods and requirements of excess spoil fill construction, and the to-date stability record of the fills. The interest in excess spoil minimization and how it affects valley fill construction is also discussed. Most importantly, we will review long-standing issues pertaining to proper design and construction measures with respect to durable rock fills and discuss how they will become more critical as spoil minimization is practiced.

Jan 1, 2007

By Dale K. Nash

The authors have developed a com¬puter-assisted critical path planning and scheduling model to help reduce time required to move longwall mining units. The model includes time constraints and limited resource constraints, such as manpower, machinery, supplies, work space, and transportation routes. Outstanding results were achieved on the first move to which the computer-model pas applied; e.g., downtime due to the move was cut by 50%. The model and the schedules developed using it provide an excellent blueprint for future moves and have led to significant savings in time and costs for Emery Mining Corporation, Huntington, Utah.

Jan 1, 1983

By Edwin H. McKee

Eruption of rhyolitic ash-flow tuffs in the area of the McDermitt (Cordero) caldera began about 17.4 m.y. ago and continued for about 1.5 m.y. During this period of silicic eruptions, a circular area about 30 km in diameter collapsed to form a caldera that subsequently filled with sedimentary and volcanic rocks. 3 A total of more than 200 km of silicic rocks was erupted from the volcano. The final phase of igneous activity, about 15.5 m.y. ago, included resurgent doming and intrusion in the central part of the caldera. Three to 4 m.y. later +I2 m.y. ago), hydrothermal solutions using the northern part of the caldera ring fractures as conduits deposited cinnabar, pyrite, alunite, and other minerals in tuffaceous lake beds and volcanic rocks accumulated within the caldera. The ore-forming solutions may have been a residuum from the silicic magma or connate water or ground water heated by the still-hot resurgent magma in the central part of the caldera. The source of the mercury has not been identified. Later oxidation of the sulfide minerals and redistribution of the supergene minerals corderoite, several mercury nitro-oxychlorides, marcasite, iron, and titanium oxides in the sedimentary rocks account for most of the newly discovered ore body at Cordero.

Jan 1, 1976

By Chris McKee

Quartz has been of interest in occupational health for years because it can cause silicosis after prolonged exposure. New OSHA regulations (Air Contaminant; Final Rule) list perlite as a nuisance dust. They conclude that perlite is nontoxic when air-borne total particulate concentrations are 15 mg/m3 or below and when quartz content is less than 1% crystalline silica. OSHA has established an 8-hour PEL of 15 mg/m TWA for total perlite dust containing less than 1% quartz. OSHA has established a 5 mg/m3 TWA PEL for respirable perlite. These limits will protect workers from significant risk of eye, skin, or other physical irritation. This regulation is based on a Group 2A classification as a probable carcinogen in humans, at the 0.1% crystalline silica level, by the International Agency for Research on Cancer (IARC 1987a, b). IARC found sufficient evidence for carcinogenicity of crystalline silica in animals and limited evidence in humans. Perlite is not listed as a carcinogen by OSHA or the National Toxicology Program.

Jan 1, 1990

By P. M. Soupios

There is an increasing requirement for geophysical surveys carried out during geotechnical investigations to provide direct information about rock quality or other geotechnical parameters. With the paucity of information to correlate geophysical results with actual rock properties, this is still difficult to achieve and additional research effort needs to be performed to address this issue. Nowadays, several researchers have been described detailed studies which designed specifically to investigate this matter. Generally, geophysical techniques which are used to estimate seismic velocities in the subsurface focus on the low strain levels that are not large enough to induce significant nonlinear, nonelastic stress-strain behavior (Luna and Jadi, 2000), which is normally evaluated when addressing liquefaction potential of soils in the shallow subsurface. Soil parameters relevant to seismic ground response (Rechtien, 1996) are density, relative density and void ratio, permeability, shear modulus, water saturation, soil fabric and stress history. Detailed characterization of elastic properties near a major construction site (e.g. a bridge) is useful for near field dynamic analysis of soil-structure interaction (SSI) effects. The coupled effect of the bridge foundation (piles, piers or abutments) and the soil immediately surrounding these substructure elements is essential for dynamic SSI analysis of these critical bridge structures. This paper presents a geophysical investigation performed along the under construction highway of Egnatia Odos, approximately 13 km west from the town of Xanthi in N. Greece. Twelve geotechnical boreholes, drilled at the maximum depth of 75 m, approximately located 20 m from the Nestos River. The objective of the survey was to obtain the high-resolution compressional and shear wave velocities of the shallow subsurface for computation of elastic engineering properties of the unconsolidated material interposed between the investigated boreholes. Joint interpretation of borehole logs and velocity images obtained by P- and S-wave traveltime inversions outlined shallow geological anomalies.

Jan 1, 2005

By B. Hines

Grinding efficiency in a vertical stirred mill is affected by a wide range of process and mill configuration variables. Of these, the media fill, size, and intrinsic density have a significant effect on power draw and grinding performance. Media-related factors that influence grinding performance include, e.g.,a higher media filling providing additional particle breakage sites, or a lower bead density decreasing the running torque at a given media filling. It has been estimated that the grinding media can cause up to a 30% change in the specific energy required to grind. FLSmidth has generally recommended that the intrinsic density (specific gravity) of the grinding media be more than triple the slurry density. This density difference helps to ensure that sufficient stress intensity is generated in the mill to provide particle breakage. It also reduces the chance of media ?float? if there is a spike in either slurry density or slurry flow rate. The VXPmills have historically operated at slurry density values between 1.2 and 1.5 kg/L, which translates to nominal bead intrinsic density range between 3.6 and 4.5 kg/L. The current trend towards regrinding bulk flotation concentrates to even finer sizes, to improve recoveries of fine grained minerals, has provided motivation to consider closed-circuit operation of stirred media mills. The slurry density in this application is typically higher than in open-circuit operation due to the higher percent solids in cyclone underflows. An additional effect is that closed-circuit operation increases the potential for media float due to higher flow rates as slurry is recycled to the mill. The normal progression in extending the operating range of existing equipment is to carry out laboratory testing before pilot-scale and plant-scale trials. The results presented in this paper examine the media density to slurry density ratio and its effect on grinding performance.

Feb 23, 2014

By R. Bishop, J. Baggett, J. Monsalve, J. Hole, N. Ripepi, A. Abassi

This work focuses on the operational and safety issues associated with karst voids in large opening underground mines. Issues include water inrush, structural instability, and engineering uncertainty in these environments. Coupled with the fracturing prevalent in folded sedimentary rocks, karsts are complex and challenging ground control risks. Traditional methods of predicting karst locations, such as probe drilling, are impeded by the inconsistent spatial distribution and variable sizes of the features. Ground penetrating radar (GPR) is a geophysical technique that transmits radio waves into a medium and subsequently detects reflected waves via a receiver. The travel time and energy of received signals are then processed and interpreted. The difference in material properties between limestone and open karsts causes strong reflections. GPR is frequently used as a geophysical surveying technique in several industries, however there is a lack of published research on underground mining GPR applications. The purpose of this work is to prove the viability of GPR in underground stone mines for karst detection, and to discuss the importance of karst detection ahead of mining. INTRODUCTION The Mine Safety and Health Administration (MSHA) currently lists 116 active underground stone mines in the United States, the vast majority of which extract limestone for crushed stone products. These limestone mines have the potential to encounter karst voids at some point in their operation, as most karstic regions of the United States develop in limestone rock masses (Kuniansky, Weary, & Kaufmann, 2016). Karsts, the cavities formed by the dissolution of carbonate rock, have long plagued the mining and tunneling industries, as well as been a hindrance on the Earth’s surface, producing sinkholes and ruining otherwise valuable land for construction and public use. The impact of karsts on the Gavarres tunnel in Spain is well documented by Alija et al; constant instability conditions, material spills into the tunnel, and unexpected cavities seriously delayed the project deadlines and “were not foreseen in the design” (Alija, Torrijo, & Qunita-Ferreira, 2013). At the water supply project in Sohngua River, China, Bin et al detail the presence of both water and sediment filled karsts which are sources of disastrous conditions at this tunnel (Bin, et al., 2017). A hydrological tunnel in Lebanon encountered numerous massive karsts in the tunneling path which required remediation via friction anchors, rockbolts, welded wire fabric, channel steel arch segments, invert steel beams, and shotcrete (Leech, Jaoude, & Ghanem, 2008). From a design standpoint, rock mass classification schemes, such as the RMR from Bieniawski and the Q-system from Barton, are not able to represent the true nature of a karstified carbonate rock mass, and therefore complex case-by-case analyses of underground conditions are necessary (Andriani & Parise, 2017).

Jan 1, 2019

By Sylvain J. Pirson

A fluid mining process has been developed by the writer whereby phosphate deposits are leached in place through the injection of a weak and recoverable acid solution much in the same manner as in the recovery of oil by water-flooding. The phosphate mineralization is dissolved In place, selectively treated in a surface plant and a high grade diacalcium phosphate substatially free of fluorine (hence of feed grade quality) is recovered. Because of its finely divided and powdery state, the plant product is highly desirable as stock material for the manufacture of triple-superphosphate and of high grade phosphatic chemicals. Details of well completion, fluid injection, areal sweep and solution efficiency, plant design and economics are presented The rate of return on investment is particularly attractive under conditions of shallow occurrence of the phosphate mineralization such as in the Bone Valley formation of Florida. The process may also be applied economically to the Phosphoria formation of wide- spread occurrence in the Northwest United States through the application of selective formation fracturing (or Hydrofrac) previous to fluid mining operations.

Jan 1, 1959

By George K. Mitteer

The Cowles Mountain Tunnel was driven 2,073 m (6,800 ft) with a 3.43 m (11 ft 3 in) shuffle shoe TBM, for the San Diego County Water Authority, through extremely high strength granitic rock in the City of San Diego, Ca. The initial contract was $10.9 million. Tunneling began in March 1992 and all work was completed in May 1993. After the tunnel drive was completed in September 1992, a 2.44 m (96 in) Welded Steel Pipe was installed, welded and encased with cellular backfill to complete a small portion of the County's $970 million Capital Improvement Project. This paper will discuss the successful completion of a tunnel through some of the hardest most abrasive rock ever excavated with a TBM in North America.

Jan 1, 1995

By M. J. Laurila

Simulation of coal preparation circuits is becoming a widely practiced technique used for the design of coal preparation plants. On a much more limited basis, simulators are finding application in off-line process control. A typical application in the latter category involves inputting projected coal washability data for a shift into the simulator and using the software to optimize product quality and recovery within a range of predefined specifications. The plant is then operated at SG?s of separation determined from the simulation exercise for the one shift time period. This procedure is useful in that it incorporates some form of advanced planning into preparation plant operations. There is an attempt made to reflect changes in feed coal quality on a shift by shift basis rather than continually running the plant near design specifications with changes in SG?s of separation being made in response to an inadequate sampling program which only provides a spot measurement of material that has already passed through the plant. Instead of instituting changes on a shift by shift basis, NHI has proposed a method whereby monitoring three major operating parameters, * Feedrate to jig * Flowrate from hydrocyclone overflow * Density from cyclone overflow the ongoing plant operating performance can be accurately predicted on a continual basis, i.e., updated hourly. Using a distribution curve to predict the split between the clean coal and refuse from a given separator does not account for variations in efficiency that occur as a result of variations in operating parameters. NHI and Arch have studied the effect of both jig loading and solids content in the recirculating load to the jig on product quality. As a result, relatively simple measurements can be made on-line in a preparation plant which will provide input data to the simulation program that enables the prediction of jig/hydrocyclone circuit performance on a real time basis.

Jan 1, 1985

By R. A. Williams

Surface and electrochemical techniques have been used to describe the surface chemistry of ferrosilicon powders, as a function of pH and electrochemical potential, for conditions typical of operating DHS plants. The practical consequences on the likely corrosion behaviour and associated electro- kinetic particle-particle interactions (which affect stability to sedimentation) in the suspension, are discussed.

Jan 1, 1987

By A. Pomianowski

A spectrophotometric study of xanthate solutions alone and their mixtures with equimolar amounts of alkyl trimethyl ammonium bromide (CnTAB) has established the additivity of ultraviolet spectra (190 - 400 my) for potassium ethyl xanthate (KEtX) and C12TAB. No obvious effect of C12TAB addition on the decomposition rate of KEtX was observed. The kinetics of collector abstraction by copper, nickel and sphalerite powders were studied in 10-5 - 10-3M solutions of KEtX alone and in equimolar mixtures of KEtX and C12TAB. Presence of C12TAB caused a 2 - 3 fold increase in the amounts of xanthate (equivalent to many monolayers) abstracted by copper and, nickel powders but had no effect on the abstraction of xanthate by unactivated sphalerite. The adsorption of C12TAB itself from the mixed solutions was very low, at most ore monolayer only, and was not influenced by the nature of the solid powder used. The results are interpreted in terms of molecular associations and synergistic action of xanthates and quaternary amines.

Jan 1, 1963

By Bruno Bussière, Michael Aubertin, Robert P. Chapuis

Covers with capillary barrier effects (CCBE) have been used in recent years as gas barriers for the isolation of wastes, including reactive mine tailings. Capillary barrier effects help to maintain a high degree of saturation in the moisture retaining layer, which then reduces gas flux. Various factors affect the degree of saturation of the moisture retaining layer in a CCBE, such as the material water retention characteristics and layer thickness. Slope geometry can also influence the hydrogeological behaviour of a CCBE, but this factor has frequently been ignored in the past. In this paper, the authors show some results of a numerical study that illustrates the influence of slope on the behavior of capillary barriers made of different types of material. The numerical model calculations are based on an actual case of a CCBE constructed in northern Quebec. This investigation shows that the water content profile is greatly affected by the position along the slope. Thus, it is necessary to evaluate the influence of the geometry to properly establish the performance of a cover system.

Jan 1, 2000

By V. Srajer

Operations research includes the application of systems analysis to mining operations, the acquisition of field data and the creation and verification of computer models of these operations. These activities result in the generation of computerized mine planning tools which have a firm base-in observational facts. The Surface Mining Laboratory of the Canada Centre for Mineral and Energy Technology (CANMET), in Devon, Alberta has been engaged in operations research activities since 1982. The work includes computer simulation of truck/shovel, continuous mining equipment and dragline operations. Other examples include cooperative programs with industry (such as the demonstration and evaluation of an integrated truck management system), the development of a device to measure off-highway truck rolling resistance, and an automated remote data transmission network. The presentation outlines existing and proposed research projects of the Operations Research group.

Jan 1, 1989

By S. D. Van Nort

The Grasberg porphyry copper-gold deposit of Freeport Indonesia Inc., an 81% owned subsidiary of Freeport-McMoRan Inc., lies within the Ertsberg Mineral District in central Irian Jaya, Indonesia. The Grasberg deposit was discovered during a drilling campaign initiated in early 1988. Production at the open pit Grasberg deposit commenced in December 1989. The Grasberg copper-gold orebody is contained with a young igneous complex of dioritic composition which intrudes limestones of the Tertiary New Guinea Group. Alteration is typical of porphyry copper deposits worldwide except that higher grade primary chalcopyrite with significant gold values is associated with a centrally located zone of strong quartz stockwork.

Jan 1, 1991

By Herbert F. Nyberg

The Black River Falls Mine is owned and operated by Jackson County Iron Company, a wholly owned subsidiary of Inland Steel Company. It is located in vest central Wisconsin, seven miles east of the city of Black River Falls. This is the first taconite plant in the state of Wisconsin. Iron mining started in this area in 1856 but soon failed due to the low grade ore and crude methods of mining and transportation. Inland Steel Company acquired the property in 1939. Some drilling and test work was done in 1940, but the economics of developing the property at that time were not favolable. Improved methods of concentrating and pelletizing in the 1960's made it possible to build the present plant. Due to the limited ore reserve of 45,000,000 tons with expected recovery of 33% it was necessary to limit the capacity of the operation to 750,000 TPY with a life of 20 years. There was some concern about an operation of such limited capacity. A million ton operation was considered the minimum size plant for a profitable operation.

Jan 1, 1976

By H. F. Haller, H. C. Pattison

The research program described in this paper is sponsored by the Advanced Research Projects Agency of the Department of Defense and monitored by the Bureau of Mines, United States Department of the Interior. PROGRAM DEVELOPMENT While Holmes & Narver is better known in other fields, the company has been active in many phases of underground excavation for over twenty years. In the 1950's, H&N participated in design and construction of nearly twenty miles of waste disposal tunnels in Southern California. As Architect-Engineer for the Atomic Energy Commission, we had design and management responsibility for many miles of tunnels and for thousands of feet of exploration and big hole drilling, from coast to coast in the States, and for gas well completions and exploration drilling for the Navy and the National Science Foundation from Pt. Barrow to Byrd Station in Antarctica. In my ten years with the company, we contributed to the development of big hole drilling techniques at a number of sites and analyzed the capability of boring machines for many of the tunnel projects. In a 1965 engineering study of a hundred miles of vehicular tunnels in rock under New York City, we investigated

Jan 1, 1997

By Gary A. Campbell, William A. Vogely

INTRODUCTION The theory of mineral demand often is slighted in the study of mineral economics. The supply side of the mineral industries usually commands a great deal more attention and effort by mineral economists than the demand side does because the study of mineral supply includes topics such as exploration, resource availability, and exhaustion theory that are generally considered unique to the mineral industries. Mineral demand, on the other hand, is thought of as being more general in nature and therefore of less concern to mineral industries specialists since it is similar to the demand for other inputs of production. This similarity with other inputs of production, however, does not negate the importance of a thorough understanding of mineral demand. It is the interaction of supply and demand that determines market behavior and not supply alone. Mineral demand is a key component among the factors that influence mineral production; there- fore, a good understanding of mineral demand can give one better insights into the industry behavior and trends than one would otherwise have. A strong working knowledge of the demand side of the mineral industries is a powerful tool for analyzing and predicting mineral market behavior. The material presented in this chapter does not depend on any special background in economics and should be accessible to all interested readers. The chapter is organized so as to permit an orderly progression of the basic topics of the theory of mineral demand while allowing digressions on related issues of special interest. The first section of the chapter is on the determinates of mineral demand. The discussion be- gins with the introduction of consumer demand and some of the necessary terminology of economics and proceeds to the particular case of the derived demand for an input of production such as minerals and the characteristics of such demand. The second section of the chapter is on the response of mineral demand to changes in economic variables like price and aggregate income. This second section of the chapter be- gins with a general presentation of elasticity of demand and continues with the particular case of the price responsiveness of mineral demand and its nature in the short and long-runs. A brief look at the response of mineral demand to price changes for other products is also included. The chapter concludes with a discussion on the effect of aggregate income changes on mineral demand and its nature in the short and long-runs.

Jan 1, 1985

By Ernest M. Spokes

Starting in 1980, a committee of the National Research Council studied the question of why some underground coal mines are safer than others and what could be done to improve the ones with poorer performance. The results indicated that safety is improved by management commitment to safety, by cooperation between labor and management on safety matters, and by quality training of employees and managers. Younger mines have higher accident frequencies, but are less likely to be killed or permanently disabled by a lost-time accident. Methods for improving safety performance are proposed.

Jan 1, 1983

By J. Vaino Huhta

An exploration program which covered an area of about 17 000 km2(6564 sq miles), was carried out between 1966 and 1969 by the United Nations project named "Mineral Survey of the Azuero Area." The target became Cerro Petaquilla, Province of Colon, Panama. See Fig. 1. Regional exploration led to discoveries of many geochemical anomalies and minor mineralization, but it was only toward the end of the project that a promising target was indicated by a large zone of comer and molybdenum anomalies in stream sediments in a remote 1, area between the Cordillera and the Caribbean coast. Follow-up surveys established the presence of porphyry-type copper mineralization in the area now known as Cerro Petaquilla.

Jan 1, 1991