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By Nancy J. Wheatley

I. INTRODUCTION The Massachusetts Water Resources Authority (MWRA) is a regional water and sewerage authority which provides wholesale water and sewer services to the Metropolitan Boston area. The MWRA was created by the Massachusetts Legislature as an independent authority in 1985 following the filing of a lawsuit in federal court to correct the pollution of Boston Harbor resulting from inadequate and inadequately maintained sewerage facilities. Immediately upon its creation, the MWRA began to tackle treatment plant issues, including addressing the need for a secondary treatment plant, planning for ceasing ocean discharging of sludge, and making interim repairs to the existing, antiquated treatment plants. The MWRA's initial activities led to a court-ordered schedule for construction of a single new primary and secondary treatment facility, for development of sludge management plan focussed principally on reuse, and for completion of a short term program of repairs to existing facilities. Once a schedule for completing these activities had been negotiated, the U.S. Environmental Protection Agency (EPA), a plaintiff in the federal court case, asked that the MWRA take "responsibility" for controlling discharges from combined sewer overflows (CSOs) within its service area. Combined sewers (sewers in which both sanitary sewage and storm water runoff are carried in a single pipe) presently discharge over 10 billion gallons of untreated wastewater into Boston Harbor and its [ ]

Jan 1, 1991

By M. R. Yalamanchili, J. D. Miller

Discussion by M.R. Yalamanchili and J.D. Miller The authors, M. S. Celik et al., should be recognized for their efforts to describe the flotation behavior of boron minerals. In the case of borax and other soluble salt minerals, analysis of the flotation chemistry has been difficult because of the high ionic strengths associated with these soluble salt systems. However, considerable progress has been made in this area, and recently a surface charge/collector colloid adsorption model was proposed by Miller and his coworkers to explain the collector adsorption phenomena observed in soluble salt flotation systems (Milleret al, 1992; Yalamanchili et al., 1993; Miller and Yalamanchili, 1994; Yalamanchili and Miller, 1994a: Yalamanchili and Miller, 1994b). In this work, the sign of the surface charge of alkali halides in their saturated brines was established on the basis of nonequilibrium electrophoretic mobility measurements by laser-Doppler electrophoresis (Miller et al., 1992). Generally, these results are what would be expected from the simplified lattice-ionhydration theory. This electrokinetic information coupled with the stability and prevalence of collector colloids in such soluble salt flotation systems indicates that the selective flotation of alkali halides is due to the adsorption of oppositely charged collector colloids by heterocoagulation. Experimental flotation/bubble attachment results for 21 different alkali halides (Yalamanchili et al., 1993; Yalamanchili and Miller, I994b) confirmed that the flotation response of soluble salt minerals with weak electrolyte collectors can best be explained by the adsorption of oppositely charged collector colloids rather than by the adsorption collector ions and/or neutral molecular dipoles as originally suggested by many researchers (Fuerstenau and Fuerstenau, 1957; Schubert, 1967; Roman et al., 1968). In addition, the flotation of certain alkali oxyanions (Pizarro et al., 1993) and double salts such as schoenite and kainite can be explained by the same collector colloid adsorption mechanism (Miller and Yalamanchili, 1994). The borax flotation results reported by Celik et al. need to be examined in terms of the above mentioned surface charge/ collector colloid adsorption model. Unfortunately, the authors seem to be unaware of this recent work that nicely describes soluble salt flotation with weak electrolyte type collectors such as amines and carboxylates. In view of our past work, the flotation characteristics of borax were of particular interest, and, in this regard, the results of dodecyl amine flotation of borax reported by Celik et al. have been examined in further detail in the light of experimental results from our laboratory. In our research, a vacuum flotation technique was used to study the flotation response of borax (Na2B407.10H20), which has a solubility of 39 g/L at 25 °C) with dodecyl amine hydrochloride as collector. These chemicals were purchased from Eastman Kodak and used as received. Saturated solutions of borax at desired pH values were prepared by continuously stirring the salt solutions over a period of about 10 hrs. It should be mentioned that the conditioning time to achieve equilibrium is an important variable and can significantly change the flotation response of some soluble salts (Yalamanchili et al., 1993). Collector was added to the saturated borax solutions containing about one gram of 100x 150 mesh borax particles, and conditioning was done for about 20 minutes prior to flotation. The borax flotation recoveries from saturated brine are presented in Fig. 1 as a function of collector addition at the natural pH of 9.3, as reported both by Celik et al. and as measured in our laboratory. In addition, the region of precipitation for the dodecyl amine hydroborate is included in Fig. 1. It can be seen in Fig. 1 that the flotation response curves are separated by about one order of magnitude in R12NH3CI collector addition. The flotation results of Celik et al. show that the maximum borax recoveries can be obtained below the solubility limit of the dodecyl amine hydroborate collector. However, in our experiments borax flotation seems to occur only after the precipitation of the dodecyl amine hydroborate collector as might be expected from the collector colloid adsorption model (Yalamanchili et al., 1993) if borax were negatively charged. Further analysis by nonequilibrium and equilibrium electrophoretic mobility measurements for borax indicates that borax is negatively charged at the natural pH of 9.3, as discussed below. The reliability of the nonequilibrium electrophoretic measurements has been demonstrated previously for alkali halides and alkali oxyanions (Miller et al., 1992; Miller and Yalamanchili, 1994). The equilibrium and nonequlibrium electrophoretic measurements for borax were found to be consistent and are presented in Table 1. These results provide clear evidence that borax carries a negative surface charge in its saturated brine (pH 9.3), and the sign of the surface charge of borax reverses and becomes positive if the pH is reduced to 8.6. The equilibrium between borax and its saturated brine can be described by the following reaction: [2Na2B407.1OH2O-4Na++B407=+HB4O7 +OH+19H20] It appears that the oxyanions of the borax lattice provide

Jan 1, 1995

By Richard H. Lindgren

I appreciate this opportunity to discuss with you OPIC's new policies designed to assist U.S. minerals companies in developing new sources of minerals overseas. A comparison of recent figures on U.S. investment in mineral exploration, development and production gives results which are remarkable --and disturbing. Through the 1960's the flow of U.S. foreign direct investment in mining and smelting in the developed and less developed countries were nearly equal. However, by 1973, roughly 80% of all exploration expenditures by mining companies was taking place in the developed countries and principally in the U.S., Canada and Australia. Clearly it is to the interests of both the developing countries and the United States to put these figures back in better balance. As you may be aware, the administration as a whole is examining systematically what can be done by government to reduce the disincentives and increase the incentives to mineral investment in the less developed countries --the LDCs. A subgroup of the National Advisory Council chaired by the Treasury Department has been formed to coordinate U. S. Government policy and program efforts relating to mineral and energy development in these countries. Among other matters, this subgroup will examine how public policies could positively influence the private investment decision-making process in the minerals industry.

Jan 1, 1978

By Henry R. Tiedemann, Eugene H. Skinner, George E. Wickham

Improving the state-of-the-art of tunneling is a continuing challenge to those involved in underground construction. New methods and procedures are usually evolved over a relatively long period of time as compared to advancements in other types of construction. To a large extent this is probably due to the fact that tunneling deals with a material or medium - the rock structure - whose physical properties are not only extremely varied, but in many instances virtually unknown until time of penetration. This hovering of the unknown tends to make "non believers" of many and at best leads to a general reluctancy of accepting new ideas or procedures. The situation is further complicated by: 1) discrepancies in terminology and respective meanings as used by different disciplines to describe, define or evaluate pertinent factors and their relative effect on the tunneling process and 2) the fact that no two tunneling situations are identical with respect to either geological conditions or construction and contractual requirements. In spite of the above there have been many successfully completed tunnels which make it apparent that both the technical and practical expertise needed to develop or project improvements is available within the industry. It is with this in mind that the RSR concept was developed. BACKGROUND This paper presents the findings and results obtained from contin-

Jan 1, 1974

By D. C. Edwards

In an age where customer service and quality drive today's industry and business, no service or product is exempt from these demands. Industry and business are streamlining everything from people to equipment and today have a heavier reliance on the performance and quality of their assets and equipment, (one of the keys to staying competitive). In the mining process industry, the centrifugal slurry pump is a key piece of equipment that keeps product moving and aids in generating revenue for its owner. The continued improvement and customer success lies in a team effort between the mining industry and the pump manufacturers. We, the pump manufacturers, need to keep improving our designs to further extend the life of our pump with fewer failures and promote to our customers proper maintenance of the pumps to continually keep unexpected failures to a minimum. Strict equipment maintenance, as thoroughly demonstrated by the military, is key to the long life and success of any piece of equipment. In the often harsh duty of the centrifugal slurry pump, maintenance is something that requires "attention to detail". No area of the pump is exempt from attentive maintenance. Here, discussions will focus on the areas of the mechanical drive end, wet end, seals, and extended pump shut down and start up. There has not been a slurry pump designed to maintain or repair itself. So in effect, each pump warrants able bodied maintenance persons to maintain them who continually observe all the rules of safety. Prior to any maintenance discussion or action, the issue of safety should always be addressed. Here, as with everywhere, the same rules apply. Work at a safe pace, note all safety precautions, use associated safety equipment and personal protective attire, observe all tagout and lockout procedures, and most importantly, be aware.

Jan 1, 1996

By Prakash M. . P. E. Donde

1. INTRODUCTION The Washington Metropolitan Area Transit Authority (WMATA) has often taken a leading role in introducing innovative construction technologies to build its transit system. Most recently, Contract Section E-5a, which included Fort Totten Station and Tunnels was constructed utilizing the New Austrian Tunneling Method (NATM) in soft ground. Along with the station and tunnels, two permanent shafts were also constructed in soft ground employing the NATM technique. This project is located within the District of Columbia on the Greenbelt Route. The subject of this paper is to discuss the unique method of construction of these two shafts, and explore the benefits of applying the NATM technique to the construction of deep shafts. The design of the shafts was performed jointly by Jenny Engineering Corporation of Springfield, New Jersey, and Mayreder Consult of Linz, Austria. The designers also provided construction support services and a resident NATM expert at the site during construction. The construction of the project started in April 1988 by a joint venture of Mergentime Corporation and H. T. Construction, a subsidiary of Hochtief Company from Germany. This $48.7 million construction project has been completed. 2. SUBSURFACE CONDITIONS The two NATM shafts are located primarily in Cretaceous-age deposits that are over 100 million years old. These deposits are intermixed and lenticular in nature

Jan 1, 1993

By M. Fig, J. Brune, C. Strebinger, G. Bogin, J. Grubb

"Although it is known that explosive gas zones can form and sustain combustion in a longwall coal mine gob, a complete account of the interaction of the methane flame and gob remains obscure. The goal of this study is to examine the impact of several gob parameters such as packing orientation and void spacing. The impact of ignition location is also detailed. A series of experiments with methane flames were performed in a horizontal cylindrical quartz reactor. The reactor was tested both empty and packed with an obstacle wall consisting of spherical glass beads to investigate the impact of various gob parameters. Results demonstrate that methane burning velocity is sensitive to all parameters investigated, and most sensitive to packing density and ignition location. INTRODUCTION The explosion at the Upper Big Branch Mine in 2010 and several other underground longwall coal mine fires and explosions show that explosive gases can mix with fresh ventilation air creating explosive gas zones (EGZs). Investigative reports of these fires have found that EGZs are able to move from the gob and into the active longwall face, endangering workers and equipment [1]. Currently, researchers at the Colorado School of Mines are using computation fluid dynamics (CFD) modeling to predict the location and movement of EGZs in the gob and along the longwall face [2,3]. It is the goal of this work to validate combustion models [4] that include interactions of the flame and the gob for future incorporation into ongoing CFD modeling of EGZs [2,3]. Throughout the years, there has been significant research investigating how flames interact with obstacles and propagate through porous media [4,5,7-11]. Since there is limited access to the gob in a longwall coal mine (Figure 1), the orientation and size of rocks and void spaces within the gob is unknown. Experiments of a simulated gob have been performed in a large scale flame tube in order to investigate the effect of scale (Figure 2) [4,5]. However, the variation in rock spacing, rock orientation, and void location makes it difficult to determine the impact of each of these parameters on methane flame dynamics. This study aims at gaining a stronger fundamental understanding of gob parameters such as spacing, orientation, and ignition location on methane flame propagation. The results from this study will provide a basis for experimentation in larger explosion vessels and will be used to validate methane combustion models for incorporation into longwall ventilation models of EGZ movement [2,3,4]. BACKGROUND Researchers have been studying flame propagation across obstacles and porous media for many years using various fuels and experimental setups [4,5,7-11]. Experiments have been performed in horizontal chambers with both ends open [7], horizontal chambers that are semi-open [4,11], horizontal chambers with both ends closed [8], and vertical arrangements [9,10]. Due to the variation in experimental setups and methods of characterizing flame dynamics such as flame speed, peak overpressure, or burning velocity it becomes difficult to directly compare results. Flame speed is a property of the mixture and refers to the speed of the unstretched flame front normal to the direction of propagation. This study characterizes the flame by its burning velocity, which is the difference between the flame speed and the speed of the unburned gases just ahead of the flame front. However, some references use the terms flame speed and burning velocity interchangeably. In this study, a semi-open quartz cylindrical reactor was used to determine methane burning velocity, which was used as a basis for comparison to determine the impact of obstacle configuration on methane flame dynamics. The quartz reactor also has the unique ability to allow for flame visualization. These features allow for faster combustion model validation [4]."

Jan 1, 2017

By P. L. Sibrell

Previous research by the U.S. Bureau of Mines showed that autoclave cyanide leaching of used automobile exhaust catalysts for recovery of platinum group metals (PGM) was technically feasible. This work involves a more detailed investigation of the chemistry of the dissolution of PGM in cyanide solutions. The PGM species in solution identified by ultraviolet spectroscopy. Pt and Pd cyanide complexes were square were The planar in geometry, while the Rh complex was octahedral. The rate of dissolution of the PGM was also investigated using a rotating disk technique. Dissolution rates increased in the order of Rh, pt, and Pd, respectively.

Jan 1, 1994

By V. A. Evans, D. L. Hellier

Introduction Preparing a report on fluorspar economics in the US could have been somewhat complicated at one time. This was because the number of producers, both large and small, derived production from different locations through-out the western US and the southern Illinois and western Kentucky fluorspar districts. Companies, such as Allied Chemical and Williamson Mining, operated in the Jamestown district of Colorado. In Walden and Salida, CO, the Colorado Fluorspar Co. operated mines and mills. In New Mexico, both Du Pont and Allied had mines and mills. In the Illinois-Kentucky district, US Steel, Rosiclare Lead and Fluorspar, Minerva Oil Co., and Marathon Oil all produced spar for the US market. Now all of the companies are out of the fluorspar business and, with the closing of the Seaforth Mineral Co.'s Inverness Mining Co., only Ozark-Mahoning Co. survives as a domestic producer. History Ozark-Mahoning Co., as it now exists, was formed in 1946 by the merger of Ozark Chemical Co. and Mahoning Mining Co. Ozark Chemical Co. was started in the 1920s to produce sulfuric acid for two refineries located in Tulsa, OK. Mahoning Mining was originally formed by the founders of Ozark Chemical Co. and the Youngstown Sheet and Tube Co. to produce fluorspar and associated minerals from properties in the southern Illinois and western Kentucky fluorspar district. In 1937, Mahoning Mining started an exploration program, employing contractor-operated churn drills to look for reserves in Hardin and Pope Counties in southern Illinois. Based on known reserves in the area and the results of the exploration program, work was started in the fall of 1938 to build a selective flotation plant at Rosiclare, IL. The mill was completed and put into operation in August of 1939. The company's first mining efforts were in the Cave-In-Rock district just north of Cave-In-Rock, IL. The deposits in this area were of the Manto or bedded type. They have been the mainstay of the company's operations in the Illinois-Kentucky fluorspar district. In 1950-51, the company expanded its operations by purchasing fluorspar properties from Colorado Fluorspar Co. at Walden, CO. This location was operated from 1952 through 1958 and from 1968 through 1973 when it was closed permanently. In 1974, Ozark-Mahoning Co. was purchased by Pennwalt Corp. Presently, it is a wholly-owned subsidiary of that corporation. As the only major domestic producer of fluorspar in the US today, the company's ability to survive under the flood of imported material is directly related to the four major segments of its operations. These are: exploration, mining productivity, maintenance, and marketing. All are done in-house. Exploration The Southern Illinois fluorspar district is located in the most complexly faulted area of the central US. The formations are sedimentary in nature and range in age from Devonian through Pennsylvanian. The deposits are small, they range in size from a few thousand tons up to 900 kt (1 million st), with the average minable deposit being around 544 kt (600,000 st). The ore occurs in both nearly vertical vein deposits and in Manto or flat lying bedded deposits. Due to the relatively small size of the deposits and the depth at which they occur, a good low-cost exploration program is essential to ensure that new finds of ore are equal to the mining extraction rate. Ozark maintains a leased land position in Pope and Hardin Counties that will fluctuate somewhere between a low of 40 km2 (10,000 acres) up to a high of 129 km2 (32,000 acres), depending on total size of tracts leased. Most all lands are obtained through a standard lease purchase option, with a small minimum royalty per acre during the normal 10-year option period. All leases are standard and without deviation to control land cost. All land leasing is done through Ozark's geological staff, who also

Jan 11, 1986

By Tim O'neil

Attendance exceeded 4,500 minerals professionals from all over the world at SME's March 9-11 Annual Meeting and Exhibit in Orlando, FL. The exhibit, of more than 600 booths, featured 398 of the mining industry's premier suppliers. The keynote session, "Change makers in the industry," opened the meeting. The session featured Jeffrey Clevenger, president of Cyprus Climax Metals; Mark Baker, senior vice president of Modular Mining Systems, a division of Komatsu; and John Correnti, vice chairman, president and chief executive officer of Nucor. The SME meeting also featured four specialty programs: Bulk materials handling by conveyor belt, Latin American perspectives, plant operators' symposium and waste characterization and treatment. Also open to attendees were more than 60 technical sessions encom¬passing coal, the environment, industrial minerals, mining and exploration, minerals and metallurgical processing and minerals resource management. Ed Dowling was the chair of the 1998 SME technical programming committee. And Dowling, director of process management and engineering for Cyprus Minerals, acted as the host of the SME keynote session. Dowling said the mining industry has undergone incredible change over the last decade. And the forces of change continue to accelerate. These changes include globalization, regulatory pressures, technology, labor, competition, pricing and other market influences, he said. With that in mind, the SME program committee selected as the theme of this year's SME Annual Meeting, "The changing world of mining ... our role." Given some of the current commodity prices, Dowling said, the theme is timely. He also noted that a large percentage of the 60 technical sessions spoke to the evolving operational and business aspects of the mining industry as the industry crossed international boundaries. The keynote session mirrored the meeting theme by focusing on the increasing challenges and required changes the minerals industry faces. Dowling reminded keynote attendees that change is not a new idea. He said Benjamin Franklin described three types of people: Those who are immovable, those who can be moved and those who are movers. And so it was appropriate that three of the most forward-thinking movers in the business - Clevenger, Baker and Correnti - address the keynote session, Dowling said. John Callaway moderated the keynote session. He is senior correspondent for WTTW TV, the public broadcast station in Chicago. For the past 13 years, Callaway has served as host of WTTW's award-winning, primetime news analysis program, Chicago Tonight. Callaway said that the keynote changemakers are recognized as industry leaders whose vision has led to significant business transformation and results. Panel speakers, he said, will discuss how shifts in strategy, op-

Jan 1, 1998

By D. R. East

Recent experiences within certain sectors of the international mining industry suggest an underestimation of the environmental risk associated with the design of mine waste management facilities. These experiences show that the technical and managerial challenge of responsible mine waste management is not always fully appreciated. Unfortunately, the image of the mining industry's environmental performance is negatively impacted by a relatively few number of failures. This negative view overrides the many positive contributions made by the majority of mining companies. The fact that these failures continue to occur to this day in both developed and developing countries is indeed remarkable, and indicates a degree of risk-taking approaching unacceptable levels. The design requirements for tailing storage facilities are, in many cases, more demanding than those of conventional water dams, because seepage of fluids which contain dissolved metals may pose a greater threat than the mere loss of water.

Jan 1, 1999

By T. Schrauf, J. Scott

"INTRODUCTION Cyanide heap leaching of gold ores in areas with extremely low winter temperatures requires special considerations to prevent freezing of the leach solution. Factors that impact the solution temperature include ore temperature at the time of stacking and during operation, burial of drip irrigation lines, use of geomembrane covers, and heating of the leach solution. Thermodynamic modeling was performed to simulate expected ore and solution temperatures under different operating strategies for Kaminak Gold’s Coffee Gold project in the Yukon Territory. Mean monthly temperatures at the site ranged from a low of -22.5oC to a high of 13.6oC, while in situ ore temperatures ranged from -0.5 to about -1.5oC. The modeling results were used to optimize the operational parameters and indicated that a combination of drip line burial and heating of the leach solution during the winter months was required to maintain solution temperatures above freezing during the initial years of stacking, although as the size of the heap increased, heating was no longer necessary. MODELING OBJECTIVES The successful operation of a cyanide heap leach under extremely cold winter temperatures requires the implementation of operational strategies to prevent freezing of the leach solution and the ore within the heap. Thermodynamic modeling of the heap provides the means to quantify the effectiveness of these different operational parameters on maintaining the required operating temperatures to avoid freezing within the heap. The operational parameters that were evaluated with the model included: • Burial depth of irrigation lines to prevent freezing during the winter months; • Variation in the temperature of the applied leach solution (to simulate heating of recirculated solution); • Variation in the rate of irrigation including seasonal variations between winter and summer months; • Seasonal versus year-round stacking of ore (to simulate the impact of the initial temperature of each ore layer as it is stacked); • Seasonal versus year-round crushing and stockpiling of ore, including the option to stockpile ore on the leach pad in the winter (i.e. stack but not leach fresh ore in winter); • Start date for seasonal stacking; • Variation of the heap geometry over time (both vertical and lateral expansion) and the associated heat storage within the heap; • Use of thermal covers (gravel or geomembrane) over the ore during the winter months; and • Effect of crush size on heat loss during crushing, stockpiling and stacking."

Jan 1, 2016

By P. L. Yorio, D. R. Willmer

"The current paper presents the results of a study designed to explore the types of practices that are fundamentally important to developing and maintaining comprehensive risk-based health and safety management systems (HSMS) in mining organizations. Eighteen practicing health and safety (H&S) executives, managers, and professionals from a variety of mining commodities were asked to assess the fundamental importance of 20 distinct elements and 133 different practices assembled from a review of several HSMS consensus standards. The research approach assumes that developing and maintaining a robust HSMS requires unwavering attention to activities designed to either: 1) directly contribute to a risk management system’s plan-do-check-act cycle; or 2) build an organization’s internal infrastructure without which the cycle cannot be sustained. The results of this study suggest that the following areas require consistent focus and attention: Leadership Development; Accountability; Knowledge, Skills, and Abilities Development; System Coordination; Culture Enhancement; Behavior Optimization; and Risk Management Studies. Each element and its corresponding top-ranked and top-rated practices are discussed.INTRODUCTION Since the time of the Industrial Revolution, occupational health and safety (H&S) management has been a topic of practitioner thought and academic inquiry (1). In the U.S., decades of regulation and research have resulted in a surplus of prescriptive information (techniques, tools, approaches, standards, programs, practices, policies, etc.). With an abundance of such information, a simple H&S solution to address a problem in the U.S. mining industry may seem straightforward. Counter to this assertion, however, some evidence suggests that the abundance of information may create complexity and cause confusion in the minds of organizational leaders and H&S managers, ultimately discouraging the voluntary pursuit of a sound approach (2). In line with this perspective, in 2006 the U.S. National Mining Association (NMA) formed an independent commission to examine H&S management issues within the mining industry. The findings of the commission called for the mining industry to adopt a risk-based management paradigm. In the presentation of its findings, the commission stated that “…every mine should employ a sound risk-analysis process, should conduct a risk analysis, and should develop a management plan to address significant hazards identified by the analysis” (3). Grounded in the well-known plan-do-check-act cycle, the recommended risk management system allows for mines to ground strategic management choices in their mine-specific hazards and risk profiles"

Jan 1, 2015

By D. E. Walsh

The behaviour of gold particles on a spiral was studied using radioactive gold tracers. The method allowed the effect of particle size, particle shape, pulp density, feed rate, and splitter settings to be studied. Although the method has been successfully applied to other gravity concentrators, it was found that reliable results were more difficult to obtain on the spiral. However, these preliminary results show that provided suitable precautions are taken, the technique is capable of providing valuable information that cannot be obtained by conventional studies, and could be used to better optimize spiral performance.

Jan 1, 1992

By V. Galla

In the present paper, two large diameter columns 2 m tall and 1.3 m diameter filled with crushed (finer) and run off mine (coarser) heap leach materials respectively were used to perform unsaturated flow studies. Instruments measuring moisture content and matric suction were placed in the columns at different depths as water was applied at calibrated flow rates from the top of the columns. The outflows from the columns were recorded using tipping bucket rain gauge placed at the bottom of the columns. Unsaturated hydraulic parameters were also obtained for the heap leach materials, scalped (passing 4.75 mm sieve size) and whole (passing 37.5 mm sieve size) sample. The measurements obtained from the columns were later compared with unsaturated flow modeling results. The comparison indicated sensitivity towards the sample size selection for unsaturated hydraulic parameters, and initial conditions considered in the model.

Jan 1, 2009

By Pinar Eksert, Hakan Akcin

Investigations show that injuries and fatalities in mining workplaces in developing countries are increasing. In Turkey, the number of workers killed in occupational accidents in the Zonguldak Hard Coal production region per 100,000 tons of coal production is 2.83 in the private sector and 2.03 in the public sector. For this reason, it is important to conduct risk analyses in terms of occupational health and safety and to implement measures quickly. Risks are evaluated with reactive and proactive approaches. Because hazards and events are often unpredictable in high-risk areas such as coal mining, it is not practical or meaningful to plan proactively in advance for every possible situation underground, especially psychosocial risks. However, it is important to develop protective strategies and measures for unexpected events or to take a reactive approach to prevent future incidents or accidents and to identify psychosocial risks. Therefore, reactive risk assessments based on the tactics and strategies of criminology can be conducted and spatiotemporal geographic information system (GIS) techniques can be utilized, enabling managers in mining workplaces to correct assessments.

Oct 1, 2024

By David A. Holmes

After a century of variable government-supplied housing on their cold, windswept lands, and facing extremely limited natural resources and no timber, the Standing Rock Sioux Tribe has launched a study into alternative housing approaches for their people. Considering that they have little more than the soil and limited river aggregates under their feet, the Tribe has elected to consider adobe and earthen-wall construction. Earthen construction is no stranger to the Sioux lands. Smaller tribes, including the Mandan, Arikira, and Hidatsa, lived here among the Sioux in earthlodges for centuries. Such earthlodge structures were not unlike the Southwestern jacal style-a framework of upright branches and branches covered with mud-employed by the Anasazi about A.D. 700-900. Indeed, the Sioux people themselves evolved from earlier earthlodge dwellers. Indigenous peoples in New Mexico, Arizona, and neighboring Mexico have used earthen-wall housing for many centuries, reinforcing Sioux observations that this is today an earth-friendly, cost-effective, and practical approach. The Cheyenne River and Pine Ridge Sioux Reservations also recently have conducted studies on earthen- wall construction. This paper describes the search for and evaluation of potential raw-material resources for earthen-wall/adobe construction on the Standing Rock Reservation in North and South Dakota. Significant resources of clay/silt materials (8 million tons in the Striped Cloud clay bed) suitable as adobe binders and sand-and-gravel aggregate (2.5 million tons) that could support earthen/adobe construction have been identified throughout the Fort Yates Flat area on the Reservation. Also addressed is how adobe and rammed-earth construction could add to the diversity of reservation construction and address future Tribal housing and other building needs.

Jan 1, 1999

By S. Ash

Murray mine was one of the first Mechanized cut and fill underground gold operations in Northern Nevada. At the end of 2002 mine production began to decline and Murray entered a phase of remnant mining and began preparations to close down. The remaining mining took place along the ore waste boundary, in previously condemned areas, and in highly challenging ground conditions. To remain economically viable new techniques were implemented in operations, geology, engineering, and rock mechanics. These improvements pushed the edge of known and accepted mining practices and have allowed Murray to remain in operation today. History The Murray mine is located on the Jerritt Canyon property, which is located 45 miles north of Elko, NV in the Independence mountain range. Mining operations started at Jerritt Canyon in 1980 out of several open pits. In 1993 underground mining began in conjunction with a decline of surface mining operations. The transition from surface mining to underground mining moved the property into a new era. At the time there were limited examples of successful underground operations in the area from which to draw experience. Several mining methods were attempted with varying degrees of success and underhand cut and fill proved to be the most effective method. To date Murray has mined 1.2 million ounces at an average grade of .335 OPT utilizing this mining method.

Jan 1, 2006

By D. E. Munson, H. J. Sutherland

Empirical methods for describing the shape of the subsidence trough over coal mines in Europe are tested against field measurements of subsidence over longwall panels in the United States. The graphical methods developed by the National Coal Board in the United Kingdom do not correlate well with the U.S. measurements; however, the profile functions typically used on the Continent give quite acceptable fits to the data. In the case of two longwall panels mined at Old Ben No. 24 in Illinois, a trigonometric profile function appears the best choice; in the case of two longwall panels mined at York Canyon in New Mexico, an error integral function is somewhat superior. Analyses of subsidence development curves show that rate effects occur. A comparison of fitting parameters establish influence functions as an important methodology for future analysis. In conjunction with the evaluation of empirical methods, an analytic model based on material failure and bulking was developed. A key element of the model is the void-volume distribution function which establishes a mechanism for transfer of significant amounts of the mined volume to the surface. Preliminary calculations demonstrate the features of the model and illustrate close correlation to physical observations in the field. Moreover, centrifuge models simulating the subsidence process have been used successfully to demonstrate the dominant or key failure modes necessary to the analytic model. General features of the centrifuge simulations and model calculations correlate well.

Jan 1, 1982

By Richard Minnitt, Philippe Renard, Christina Dohm, Winfred Assibey-Bonsu, Matthew Aboagye, Julien Straubhaar, Mahlomola I. Mabala

The application of multiple point statistics (MPS) in oil studies has gained traction over the years; however, the use of MPS in mineral resource estimation and classification is still limited. This is despite MPS’ ability to deal with complex and heterogeneous geology better than the commonly applied two-point based methods. The availability and choice of a representative training image (TI) are often cited as the main challenge holding back MPS’ application in mining geostatistical studies. On the other hand, the general approach used in mining whereby early focus is on higher grade areas and lower grades are planned to be mined later presents a massive opportunity for the development of representative TIs. Mined-out areas provide large amounts of historical data that can be used to develop training images or training datasets that can be used to estimate in mining extension areas (often lower in grade), provided low grade areas are underpinned by similar geology analogue. This approach will enable more robust estimates in mine/pit extension areas for both high- and low-grade extensions than with traditional two-point geostatistical methods.

Jun 25, 2023