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By Birger Schmidt

INTRODUCTION Conceptual design of the first Exploratory Shaft (ES-I) for the Nuclear Waste Repository in Basalt (NWRB) began in July 1981; detailed design began in February 1982, and was largely completed by December (RKE/PB, 1983). The intent was to begin shaft construction by January 1983. The site had been prepared at that time, a construction manager selected and on board, the starter hole excavated and lined, and steel casings were under procurement. Government policy changed, however, and construction was halted before the drill rig started turning. Construction is now planned to begin in 1988. ES-I is a part of the site characterization program for the NWRB. The shaft will be used to develop production data and related information relative to drilling shafts at the site near Richland, WA, and to provide access to the repository horizon for site characterization and testing. The early program called for one shaft and some 330 m (1000 ft) of drifting. The program has since expanded to include a second shaft (ES-II) and more extensive drifting and testing. Currently, both shafts are planned to be 1.8 m (6 ft) in finished diameter, but studies are underway to determine if the second shaft should be larger. The drilling method was selected for shaft construction primarily because it offered a significantly shorter construction period than conventional shaft sinking using freezing and grouting. The finished drilled shaft will be lined with a continuous steel lining. Personnel are safer during construction with a drilled shaft than with a conventionally sunk shaft. The drilling method

Jan 1, 1987

By Stephen Hodgson, Ken Brouwer

September 2005, Northern Dynasty Mines announced the discovery of a new, high-grade deposit at its Pebble project in southwest Alaska. The product of insightful geological investigation, Pebble East, as it is now known, is quickly growing into one of the most significant copper deposits in the world. Preliminary analysis shows it could reduce the U.S. copper supply deficit by a third. The new deposit has also altered Northern Dynasty’s view of how Pebble should be developed. This article describes the Pebble project as it is currently understood and outlines the work planned for the next several years.

Jan 1, 2007

By H. Walqui

The Empire concentrator was built in four stages, with the latest stage accounting for 50% of the overall plant capacity. Over the past 5 years, the average throughput of the three grinding lines has decreased by 50 LTPH (15%) without significant changes in ore characteristics and despite the addition of secondary grinding capacity to supplement the existing pebble mills that are the constraint of the grinding circuit. This paper discusses the different areas under study that are aimed at optimizing grinding circuit utilization which includes improving system logic, pebble crushing operation and pebble mills operation.

Jan 1, 2009

By Augustine O. Orumwense

Ball mills are commonly used for regrinding operations in the mineral processing industry. But, in recent times, efforts are being made at the introduction of stirred mills particularly for those instances where very fine grinding is required. Media type (steel shot, glass beads, alumina balls and crushed quartz), media size, mill speed and the number of passes required to obtained the target product size are studied. The product size and energy consumption are used in the evaluation of the test results. The grinding media size, shape, density, filling ratio, mill circumferential speed and grinding time play a distinct role in product size fineness.

Jan 1, 2005

By S. Möllerherm, E. Drüppel

"The development of indicators to assess the sustainability of mineral raw materials operations is amajor task with respect to its actuality and difficulty. This holds true even more when dealing withenvironmental indicators.The use of existing environmental indicators in the mineral raw materials industry leads to false orat least distorted results. Therefore the Institute of Mining Engineering I from the RWTH AachenUniversity developed indicators and an assessment system for the mineral raw materials industryon operation, company and sector level on behalf of the Federal Ministry of Economics and Labour(Bundesministerium für Wirtschaft und Arbeit, BMWA) and the Federal Institute for Geosciencesand Natural Resources (Bundesanstalt für Geowissenschaften und Rohstoffe, BGR).In total 30 indicators were defined and designed to assess the performance of the mineral rawmaterials industry in terms of sustainable development, 10 indicators for each pillar (economical,ecological and social pillar).The following paper describes some of the results focussing on the development of environmentalindicators. These had to be adapted or completely new designed in order to match the specificcharacteristics of the mineral raw materials industry."

Jan 1, 2005

By Phil Pennington, D. Jack Adams

Mining and processing of minerals, metals, and fossil fuels can release selenium and arsenic into wastewaters. Both selenium and arsenic are difficult to remove to levels that meet current drinking water and discharge criteria. These metalloids can be used as electron acceptors by microorganisms transforming them back to reduced states, thus removing or stabilizing them. Bioremediation cost effectiveness will be discussed in terms of site information required, microbial populations, co-contaminants, pH, redox, and nutrients. Full-scale, economical ex situ and in situ biotreatments are possible and can produce 1,000’s of times less sludge than conventional precipitation technologies.

Jan 1, 2005

By James M. Harrington, A. Azra Bilgin, JoAnn Silverstein

The prevention of AMD in situ is more attractive compared to subsequent downgradient treatment alternatives that do not involve source control. AMD source control can be achieved by shifting the microbial activity in the sulfidic rock from pyrite oxidation to anaerobic heterotrophic activity. This is achieved by adding biodegradable organic carbon amendments to the sulfidic rock. This technique was applied in an abandoned mine pool with a pH of 3-3.5. Following treatment, near-neutral pH and decreased effluent heavy metal concentrations were achieved. In situ bioremediation by enhancement of bacterial iron and sulfate reduction is a promising technology for AMD prevention.

Jan 1, 2005

By Dan Armour

Bolting solutions traditionally offered only wet drilling or dry drilling options; each with advantages and disadvantages. Joy Mining Machinery has developed a Mist Drilling System that incorporates the best of both types of drilling. Compared to wet drilling, mist drilling offers as much as a 90% reduction in water use. As a result, floor and roof conditions are tremendously improved. This offers a safer and more comfortable work environment for operators. Mist drilling can offer a significant reduction in noise levels compared to dry drilling and in recent trials, bit life has been greatly improved. Holes are cleaner and operators experience less exposure to respirable dust.

Jan 1, 2005

By M. Botz

Anatolia Minerals Development Limited (AMDL) is constructing the Çöpler Gold Project in eastern Turkey and commenced mining in the fourth quarter of 2009 with gold production scheduled to begin in the fourth quarter of 2010. The project is a 15,500 tonnes/day oxide heap leach with three-stage crushing, agglomeration, carbon adsorption and electrowinning for final metal recovery. Leach solution copper levels are expected to be relatively low during the first two years of production but will increase in later years due to higher copper content in the mined and processed ore. Over the mine life approximately 40 million tones of ore will be placed on the leach pad, which will contain about 35,000 tonnes of copper. Metallurgical testing indicates copper extraction will vary by ore type and, if controls are not implemented, may lead to copper levels exceeding 1,000 mg/L in pregnant solution. High copper levels in leach solution have the deleterious effect of increasing cyanide consumption and potentially overwhelming the ability of the carbon circuit to effectively adsorb the principal economic metals, which in this case are gold and silver. Using data obtained from laboratory leach column testwork, the heap leach facility was modeled using METSIM process simulation software to estimate the build-up of copper in leach solution over the mine life. Laboratory testwork was also performed to evaluate process conditions for treating a portion of pregnant leach solution via sulfide addition to precipitate saleable copper as copper sulfide (Cu2S).

Jan 1, 2011

By G. W. R. Kuzyk

The Underground Research Laboratory (URL) , a major geotechnical research facility, is currently being developed by Atomic Energy of Canada Limited (AECL) , 120 km northeast of Winnipeg, Manitoba. The URL is part of the Canadian Nuclear Fuel Waste Management Program, which is assessing the concept of nuclear fuel waste disposal in a vault deep in stable plutonic rock of the Canadian Shield (Simmons, 1986). Comprehensive geotechnical research and development activities are being carried out in conjunction with excavation? and construction of the underground facilities.

Jan 1, 1989

By J. S. Limb

Actual issues which arose during the discovery process or subsequent court testimony are presented. While most of these issues relate to the author’s specialty of mineral appraisal some are more general in nature and could be of interest to those who may be involved in current or future court testimony. Several important areas to be reviewed and agreed upon with the client and their legal counsel are discussed. General observations on litigation, the discovery process, testimony and some repercussion’s are also given.

Jan 1, 2001

By Gilles Recher, Jörg Riechers, Albert Lueghamer

"INTRODUCTIONIn view of a global trend towards urbanization, more and more trunk sewers and combined sewer overflow tunnels (CSO) with medium to large diameters and the corresponding link sewers are currently built and under design. Shielded tunnel boring machines using segmental lining as tunnel support represent an efficient solution for construction of new wastewater and supply tunnels. Especially in the field of sewers, the durability of concrete structures both exposed to any groundwater present on its exterior and to aggressive waste water as well as gases on its interior is a key requirement. Despite thorough research on segmental lining and mechanized tunneling machinery, conventional thermoplastic liners show comparatively minimal progress in terms of practical advancements. This is in contrast with the development of the latest segment embedded high density polyethylene (HDPE) system. Based on experiences achieved, this paper discusses the latest development of an integral protective lining system in respect of material characteristics and its adaptability to both project and customers’ demands. Reviewed performances, as the bondage behavior of the embedded HDPE system at axial stress loads due to acting thrust cylinders during ring build as well as the ability to drain pressurized water behind the embedded membrane, tested at full scale segments, are also presented. The paper is round off by presenting first details of sewer projects endeavoring to utilize this cutting-edge solution for an integral concrete protection, which will be commenced beginning of 2016.CASE HISTORIES ENCOURAGE ADVANCEMENTS Past experience has shown that unprotected concrete surfaces as well as chemical based linings such as coatings, sprayed linings and cured in-place-systems cannot reach the desired life times. Also the fact that in deep tunnel sewer system hardly maintenance is possible, a durable and maintenance free system is required which only can be reached by applying mechanical anchored HDPE (CPL)."

Jan 1, 2016

By A. A. Bilgin

The prevention of acid mine drainage (AMD) in situ is more attractive than down-gradient treatment alternatives that do not involve source control. AMD source control can be achieved by shifting the microbial activity in the sulfidic rock from pyrite oxidation to anaerobic heterotrophic activity. This is achieved by adding biodegradable organic carbon amendments to the sulfidic rock. This technique was applied to an abandoned coal mine pool in Pennsylvania. The pool had a pH of 3.0 to 3.5. Following treatment, near-neutral pH and decreased effluent heavy metal concentrations were achieved. In situ bioremediation by the enhancement of bacterial iron and sulfate reduction is a promising technology for AMD prevention.

Jan 1, 2007

By k. Osei-Boakye

This paper presents the calibration of a real-time aerosol monitor, the TSI DustTrak?, to the NIOSH 5040 method being used by the Mine Safety and Health Administration (MSHA) for compliance enforcement evaluation. The standard NIOSH 5040 instrument for compliance evaluation of diesel particulate matter (DPM) has an inherent time lag of up to two weeks for laboratory processing of sample results. Therefore, providing the underground mines with a means of quantifying DPM conditions in real-time, will enable them to efficiently and effectively manage DPM levels to ensure compliance with the regulated limit.

Jan 1, 2009

By Charles J. Hass

INTRODUCTION Deformation measurements are some of the simplest and most useful measurements that can be made by the mining/rock mechanics engineer in assessing the sta¬bility of openings in rock. A number of tools and tech¬niques are presently available. This chapter will de¬scribe the most common instruments, their application, and present the equations needed for data reduction. MECHANICAL STRAIN GAGE Description of Instrument A mechanical strain gage of the Whittemore type shown in Fig. I is a useful instrument for measuring deformations of pillars, sidewalls, and roofs of under¬ground mines. Measurement gage lengths typically range from 51 to 254 mm (2 to 10 in.), and the dial indicator reads to 0.0025 mm (0.0001 in.). The instru¬ment measures the deformation between precision gage points which are anchored in the rock. The anchor points are typically grouted in small holes drilled 12.5 mm (1/2 in.) or so deep into the rock. Strain a is calculated from the measured deformation AL with the equation [ ] where L is gage length. A necessary accessory for the instrument is a master bar normally made from invar steel having a low co¬efficient of thermal expansion. This bar allows one to check the instrument for changes in the mechanical zero point and to correct for temperature effects on the measuring instrument. The instrument is available from Soiltest, Inc. for a cost of approximately $340; the cost of the master bar is approximately $55; and nonreusable brass inserts which are anchored in the rock are nominally priced at $0.27 each. All prices are for 1978. Applications Two classes of applications may be considered, one where only one measurement direction is involved and the second where three measurement directions are em¬ployed. Applications where only one measurement di¬rection is necessary include: monitoring crack or frac¬ture separation or shear movement with anchor points on opposite sides of the discontinuity; measurement of vertical strain in a pillar or sidewall; and measurement of steel support deformations with anchors in the steel members. The more general application involves a strain ro¬sette consisting of three measurement directions which for convenience are oriented 1.04 rad (60°) apart to form an equilateral triangle as shown in Fig. 2. Strains in the three measurement directions [ ]

Jan 1, 1982

By Karen Mikkola, Gerald Luttrell, Jaisen Kohmuench, Glen Oswald, Michael Mankosa, Tracy Westerfield

Hydraulic separators are commonly used for particle size classification and gravity concentration of minerals and coal. Unfortunately, the efficiency of these processes can be quite low due to poor equipment design and variations in feed consistency. To help alleviate these problems, an industry-driven R&D program has been undertaken to develop a new generation of hydraulic separators that are more efficient and less costly to operate and maintain. Two of the most promising technologies, the CrossFlow and HydroFloat separators, have now been tested at industrial sites. The data obtained from these sites have been used to illustrate the potential performance improvements that can be realized through the application of these high-efficiency separators.

Jan 1, 2005

By P. T. Bissert, T. J. Lutz, J. A. Yonkey, G. T. Homce

"Underground refuge alternatives require an air source to supply breathable air to the occupants. This requires pressure relief valves to prevent unsafe pressures from building up within the refuge alternative. The U.S. Mine Safety and Health Administration (MSHA) mandates that pressure relief valves prevent pressure from exceeding 1.25 kPa (0.18 psi), or as specified by the manufacturer, above mine atmospheric pressure when a fan or compressor is used for the air supply. The U.S. National Institute for Occupational Safety and Health (NIOSH) tested a variety of pressure relief valves using an instrumented test fixture consisting of data acquisition equipment, a centrifugal blower, ductwork and various sensors to determine if the subject pressure relief valves meet the MSHA requirement. Relief pressures and flow characteristics, including opening pressure and flow rate, were measured for five different pressure relief valves under a variety of conditions. The subject pressure relief valves included two off-theshelf modified check valves, two check valves used in MSHA-approved built-in-place refuge alternatives, and a commercially available valve that was designed for a steel refuge alternative and is currently being used in some built-in-place refuge alternatives. The test results showed relief pressures ranging from 0.20 to 1.53 kPa (0.03 to 0.22 psi) and flow rates up to 19.3 m3/ min (683 scfm). As tested, some of the pressure relief valves did not meet the 1.25 kPa (0.18 psi) relief specification.IntroductionThe Mine Improvement and New Emergency Response Act of 2006 (MINER Act) was enacted in the United States in the wake of three mine explosions/fires that claimed 19 lives that year. Intended to help improve underground coal mine accident preparedness, the MINER Act includes provisions that target mine safety issues in areas such as emergency response planning, adoption of new technology, training and education, and mine safety standards enforcement (U.S. Mine Safety and Health Administration, MSHA, 2006). Section 13 of the MINER Act specifically directed the U.S. National Institute for Occupational Safety and Health (NIOSH) to provide for research into the effectiveness and viability of refuge alternatives for underground coal mines. This mandate culminated in the 2009 adoption of changes to Title 30 of the Code of Federal Regulations (30 CFR) mining health and safety regulations, requiring underground coal mines to provide mine emergency refuge alternatives and associated components, to provide a life-sustaining environment for persons trapped underground. Such refuge alternatives can be either self-contained mobile units or built-inplace facilities. The regulatory changes also include provisions establishing requirements for MSHA approval of refuge alternatives and their components, and among these provisions are numerous criteria for providing a safe breathable atmosphere under positive pressure within the refuge alternatives. One specific criterion for maintaining a safe refuge alternative atmosphere requires the inclusion of an air pressure relief valve that will activate at a maximum of 1.25 kPa (0.18 psi), or at a pressure above mine atmospheric pressure, in the refuge alternative, as specified by the manufacturer when the breathable air is supplied by a fan or compressor (MSHA, 2008)."

Jan 3, 2018

By James L. Poole

The gold and silver markets from the late 1960's to the present are reviewed and the outlook for these metals in the 1980's is presented. Included in this discussion is a summary of the basic supply and demand balance for gold and silver since the mid-1960's. an explanation of the price formation for the metals, some of the relationships between the prices of these metals and selected economic parameters, and how these factors affect the outlook.

Jan 1, 1981

By Daryl E. Radcliffe, Raymond M. Stateham

The Bureau of Mines, under a Cooperative Agreement with the Bear Coal Company, Somerset, Colorado, conducted a large scale evaluation of the effect of time lapse on roof stability. Time lapse in this study is the interval between exposure and permanent support of the mine roof. The study indicates that time lapse is not a critical factor in roof stability provided permanent support is installed before catastrophic failure begins. Concurrently with the time lapse study, investigations were made of stress distribution around resin-grouted bolts, the regional stress field, and anomalous geologic conditions. The behavior of the resin-grouted bolts, at least in the Bear mine, appears to fit the Coulomb-Navier Theory. Geologic conditions are primary factors in trends of roof stability that extend across the mine.

Jan 1, 1982

By N. Ohmura, H. Saiki, T. Nagaoka

A microbiological flotation system that facilitates the removal of pyritic sulfurfrom coal is reported. The chemoautotrophic bacterium Thiobacillus ferrooxidans is utilized as a pyrite-selective biological surfactant that augments the flotation-mediated rejection of pyritic sulfur. The bacteria were produced by continuous cultivation in 50-L tanks, where it was possible to produce 3.8 x 1012 cells/day when the dilution rate was optimal and the pH was 1.6, a condition that prevented ferric precipitation. Prior to flotation, the bacteria were mixed with coal, which allowed cells to selectively adhere to the pyrite. The adherence of bacteria made the pyrite surfaces more hydrophilic, which facilitated separation by increasing the tendency of pyrite to sink, while the hydrophobic coal floated. When a synthetic coal/pyrite mixture (10.1 % sulfur) was subjected to microbial flotation, the level of sulfur rejection was stable during the entire period of operation (i.e., one hour). In the absence of bacteria, flotation reduced the sulfur content of a coal/pyrite mixture to within the range of 6.7% to 7.4%, with the combustible recoveries ranging from 93.9% to 99.0%. In the presence of bacteria, the sulfur content of cleaned coal was in the range of 1.3% to 1.4%, with the combustible recoveries ranging from 80.8% to 86.3%. Bacterial activity accounted for 57% of the total sulfur rejected through flotation. The desulfurization capacity of the system was further confirmed by testing it with run-of-mine coal. The pyritic sulfur content was reduced from 2.9% in the feed coal to around 1.2% in the froth product, while 80% of the combustible recovery was retained. Microbial flotation removed 60% of the pyritic sulfur from the feed. These findings demonstrated that micro¬bial flotation could be utilized for the removal of pyritic sulfur from coal in a semicontinuous system.

Jan 1, 2000