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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 M. I. F. S. Cruz, R. Pedersen, F. J. A. S. Barriga, A. Dias, A. F. A. Marques

"Underwater hydrothermal vents are known since the 1970s and their importance for the global economy is growing as new discoveries and new assessments are made each year (Cherkashov et al., 2010; Corliss et al., 1979). The similarities of seafloor massive sulfides, representing the younger versions of the well exploited on land volcanogenic massive sulfides, bring an increased awareness to the potential of the sea (Ajan G. Galley, 2007; Hannington et al., 2011; Herzig and Hannington, 1995). The Arctic Ocean presents itself as an opportunity to study new interest areas and numerous hydrothermal systems (active and inactive) were discovered along the Arctic Mid Ocean Ridge (AMOR) (Pedersen et al., 2010b). The Mohns ridge is an ultraslow spreading ridge of the AMOR (Vogt, 1986) where two hydrothermal vent sites were recently discovered, the Jan Mayen and the Loki’s Castle (Pedersen et al., 2010a; Pedersen et al., 2009; Pedersen, 2005). Here we compare these two Arctic hydrothermal systems, which represent two well-differentiated end-members of hydrothermal fields in the region."

Sep 1, 2014

By W. G. Brunner

The slurry wall technique has undergone an evolution from its invention to its today’s status. In the early stages slurry walls were built with cable grab, later on with much stronger hydraulic grab and last but not least with the use of the cutter technique. The cutter allows thick walls with high verticality to extreme depths through hard soil and rock formations. With the rising demand of the construction of watertight diaphragm walls different joint systems have been developed. In addition to the rapid development of excavation systems it was necessary to improve slurry treatment and desanding plants, especially in conjunction with high performance trench cutters. Deep mixing methods can be used economically for the construction of cut-off or excavation support walls where other systems such as traditional soldier beams and lagging walls would yield unsatisfactory performance, where the installation of vibrated or driven sheet piles could cause vibration induced settlements and where concrete diaphragm walls would be time consuming and expensive. The new CSM method can largely replace the more conventional single or multiple auger methods of soil mixing or jet grouting. The cutter tool is similar to a cutter used in diaphragm walls or cut-off walls and is operated with a Kelly mounted on a drilling rig or rope suspended on a crane jib or mast of a base carrier. With this system much deeper walls can be installed and even hard soil layers can be penetrated.

Jan 1, 2007

By R. J. Lytle

INTRODUCTION Prior to excavation in soil and rock, it is useful to know the subsurface structure. This is important information both for safety and for equipment scheduling reasons. It is useful to know whether parts of the subsurface might be potentially troublesome or of different character than is generally thought present. By using geophysical probing, it is possible to infer the location and size of these unusual regions. The ground structure is commonly estimated from core samples taken from boreholes. These cores give a detailed knowledge of the structure in the borehole. However, knowledge of the structure exterior to the borehole can only be extrapolated from core data. By using seismic and electromagnetic cross-borehole geophysical probing, remote probing can be used to sense the region exterior to boreholes. A recent advance has significantly improved the state-of-the-art for defining the ground structure between boreholes. This new procedure utilizes large amounts of data and provides a detailed picture of the subsurface. The data processing algorithms used are similar to those in medical imaging of the human body using x-rays, a science called x-ray tomography. This imaging of the ground is called geotomography, which is a shortened acronym for geophysical tomography. Several examples of geotomography applied to imaging ground structure are presented. Our approach has been to probe the ground with electromagnetic and seismic waves. We map the region of interest with signals transmitted between multiple source and receiver pairs lowered in boreholes on opposite sides of the region (Figure 1). The received signals vary according to the transmission properties of the media

Jan 1, 1979

By H. Akbari

Ordinary portland cement (OPC) is the key pozzalonic component of the concrete mix widely used as a construction material worldwide. B illions of tons of OPC are used in the construction industry each year. However, calcinations of limestone and silica that produce OPC also produce almost an equal amount of C O2 during the cement manufacturing process. Thus, OPC production accounts for nearly 7% of all anthropogenic C O2 emissions each year. The main objective of this study was to develop a geopolymer-based composite to be used as a substitute for OPC in concrete application to significantly lower the carbon footprint of the construction industry. A waste material produced during the coal combustion process was used as the main raw material for the geopolymer-based composite. It was mostly the nonmetallic content of the F-type fly ash produced from the combustion of bituminous coal. The authors envisioned extracting some of the valuable metal oxides from fly ash prior to using the major nonmetallic portion of the fly ash for geopolymer concrete application. The results obtained from this study showed that the compressive strength of geopolymer concrete compares favorably with that of conventional concrete prepared using OPC.

Dec 1, 2013

By K. Hanson

When done properly, benchmarking is an extremely effective tool for assessing ones performance, finding areas for improvement, and identifying strengths. However, when done improperly it can be an exercise in futility and result in incorrect observations and conclusions. A primary pitfall of benchmarking is collecting too much unreliable information. Surprisingly, the evolution of data storage and the ease of data collection are not helping with better data collection. Instead, it is just allowing one to collect more information, while at the same time inundating one with too much data. Additionally, the process of data collection can be tedious and is often times delegated to the least experienced individual resulting in unreliable and incorrect data collection and entry. Another primary pitfall of benchmarking is metrics that are cost based or poorly designed. Cost based metrics typically involve comparing unit mining costs ($/tonne). Between mines, unit mining costs are not very well correlated and have become further complicated by significant regional cost variations and mining inflation in the last years. Likewise, poorly designed metrics lead to poor benchmarking results. Examples of poorly defined metrics include: metrics that rely on information that is difficult to collect, metrics that are poorly defined, metrics which are too site focused, and metrics that measure low consequence practices.

Jan 1, 2011

By W. Pariseau, S. Puri, S. Schmelter

Introduction Joints often have profound effects on elastic properties and strength of rock masses and therefore on rock slope stability. In surface mine slopes, joints are usually too numerous to be taken into account individually, so an equivalent properties approach is necessary. Previous work that treats a jointed rock mass as an equivalent composite material of joints and intact rock between resulted in excellent agreement between estimated and true rock mass elastic moduli in case of fully persistent joints (e.g., Pariseau, 1999) Rock mass failure mechanisms on joints and through intact rock were retained obviating the need for an equivalent rock mass strength. Impersistent joints, which are not continuous on a joint plane, can be accommodated (Pariseau, 2003). However, slope stability analysis of a large, deep copper mine indicated a need for computational efficiency even in two-dimensional analysis of vertical sections through pit walls (Puri, 2006). The analyses by the popular finite element method used small elements of bench size near the pit slopes and much larger elements away from the pit walls. The reasons for the graded meshes were numerical quality (small elements) and computational economy (large elements). Small elements contained only a few joints, while the larger elements contained hundreds of joints and led to impractical computation run times (days!). A new modeling procedure that recognizes sufficiently large elements as representative volume elements (REV’s) overcomes this obstacle. A companion improvement recognizes the concept of a representative area element (RAE) in association with joint impersistence and the probability that joint material occupies a considered site. Both are steps towards greater model realism and a practical slope stability analysis procedure. Consider the open pit mine photo shown in Figure 1(a), a companion plan view in Figure 1(b), and the problem of slope stability where high slope angles favor economics but low slope angles favor safety. These competing factors in surface mining generally result in some sections of the mine that have unstable slopes that require monitoring and perhaps mitigating action to improve stability. Although stability of a given section may not be easy to quantify with a single number, useful design guidance can be obtained from a finite element analysis of a proposed mining sequence leading to future pit slopes and profiles. The presence of water from rain and snow melt indicates a need for a coupled analysis that links water pressure, effective stress and total stress (Schmelter, 2001).

Jan 1, 2007

By Yi Luo

Bolting the mine roof is one of the noisiest underground mining operations. The main contribution to the noise is the drilling of the roof bolt holes, especially drilling in hard rock. Previous research shows that the specific energy consumed in drilling bolt holes is inversely proportional to the bite depth (i.e., penetration per drill revolution). Less specific energy at a reasonably high bite depth means less energy is wasted in the drilling process for producing heat, bit wear and noise. Therefore, proper control of the drilling operation to achieve a reasonably higher bite depth can reduce drilling noise from its sources as a proactive noise control approach. In order to explore the feasibility and develop the proactive technology for reducing drilling noise, drilling tests have been conducted in laboratory settings. The preliminary results show that significant reduction in noise dose can be achieved by drilling in medium hard rock with uniaxial compressive strength of about 276 bars (4,000 psi) and at a reasonably high bite depth of about 4.6 mm/rev (0.18 in./rev). This paper presents the findings from laboratory experimental studies.

By Hendrick A. D. Kirsten, A. Clayr Alexander

Stillwater Mining Company is currently developing a second underground palladium and platinum mine approximately 21 km (13 miles) west of their existing Nye operation in the Bear tooth Mountains of southern Montana. Portals for the two access tunnels required at the new site were excavated in limestone talus to accommodate4.6 m (15 feet) diameter tunnel boring machines. A review of the technical design, field conditions and construction of the portals is presented.

Jan 1, 2001

By John D. Morton, J. H. LaVerne Palmer, Douglas J. Belshaw

An extensive programme of ground instrumentation and observation was carried out for the West Duff in Outfall Sewer tunnel project prior to and during construction, to establish the performance characteristics of the rock through which the tunnel and appurtenant openings were dug and to examine the nature of the lining-to-ground interaction. The existence of high horizontal residual ground stresses was confirmed, and values established by overcoring. Rock deformations and stress changes were monitored during tunnelling. Permanent stress and strain monitoring devices were set into the final lining and these are continuing to operate. INTRODUCTION The site is located on the north shore of Lake Ontario at Pickering, some 20 miles (32 kilometres) east of Toronto, Canada where a variable thickness of glacial or interglacial sediments overlies bituminous shale bedrock of. the Collingwood Formation which is lower Ordovician age. Approximately 50 feet (15 metres) of glacial cover exists at the shaft, though this thins abruptly at the regressing cliffed shoreline such that several small areas of exposed bedrock exist in the lakebed. The general location, overall geological section and detailed site plan and profile are illustrated in Figs.1,2 and 3 respectively. General properties of the rock as established during an extensive test drilling and site investigation programme are listed in Table 1, while stress determination by USER overcoring stress meter device are given in Table ll. These data formed the basis of analyses which were done to examine the intended outfall design, and to detail the construction procedure and the observational instrumentation programme.

Jan 1, 1979

By W. Rogers

Blast-induced rock mass displacement can have a significant impact on ore loss & dilution. The mischaracterisation of the grade boundaries both prior to, as well as a result of blasting can lead to significant financial losses on account of ore loss and dilution. Ore dilution occurs when waste material is miscategorised as ore and sent for processing or stockpiling, diluting the run of mine head grade and recovery. Ore loss takes place when valuable mineral is miscategorised as waste and sent to the waste dumps, thus never being processed and recovered. Extensive research has been conducted at the University of Queensland over the last fifteen years to understand the impact of blast movement on ore loss and dilution. Recent outcomes of this research have developed innovative tools and techniques to measure and model blast movement. These techniques have been implemented at Ahafo gold mine in Ghana to understand blast movement dynamics and to implement solutions to reduce blast-induced ore loss and dilution. These solutions are validated through controlled trials and have been incorporated into site standard operating procedures to sustain the benefits.

Jan 1, 2012

By Steve Kral

The domestic mining industry may be in the doldrums but there appears to be hope, at least from a regulatory standpoint. At least one US senator believes that the events of Sept. 11, 2001 made many citizens see the need for the country to become more self-reliant on its growing energy needs. Even before that tragic day, however, the Bush administration was making a strong push to open up more public land for energy and natural resource development.

Jan 1, 2002

By James Dunn

“The strongest argument of the detractor (of mining)is that the fields are devastated by mining operations ...They argue that the woods and groves are cut down, for there is need of an endless amount of wood for timbers, machines and the smelting of metals. And when the woods and groves are felled, then are exterminated the beasts and birds, very many of which furnish a pleasant and agreeable food for man. Further, when the ores are washed, the water which has been used poisons the brooks and streams, and either destroys the fish or drives them away.” Georgius Agricola, 1556, De Re Metallica, translated by Hoover, 1950. Technical problems associated with the cleanup of historic mines are not new. Nor are they unique to the mining industry or the governmental agencies addressing them. Both face the same issues and challenges of defining the problems, evaluating remediation options and finding the most economic and effective solutions.

Jan 1, 1999

By Ralph P. Hackl

Ore at the Congress gold property, located near Goldbridge, British Columbia, is extremely refractory with most of the gold disseminated in fine-grained arsenopyrite. Metallurgical testwork conducted by Giant Bay Biotech Inc. indicated that biooxidation pretreatment was capable of increasing cyanide gold recovery from the ore to greater than 90%. To determine if the bioleach process could be successfully scaled up, a 225m' (7950-cu ft) commercial size bioleach reactor was built and tested at the mine site in 1989. At that time, the tank was the largest bioleach reactor ever operated. The objectives of the program were: • to ascertain if the biooxidation rates obtained in lab and pilot-scale reactors could be duplicated in a commercial scale tank; • to identify agitation conditions under which the process will function optimally; and • to demonstrate the bioleach process on a scale sufficient to satisfy the owners and potential investors.

Jan 1, 1990

By Peter J. Tarkoy

A great deal of attention has been directed toward the complexities and inadequacies of exploration and pre-bid geotechnical information for heavy construction projects, differing site conditions, and the adversary relationships which generally develop as a result. The adversary position has been maintained at all cost. The solution is simple, if not easy. The solution requires strict and equal adherence to given principles by all parties involved, throughout the life of the project, from conception to completion. It is necessary to review and redefine some basic concepts, without value judgements, from a context of getting the job done. In a recreated context, the role of truth, judgement, responsibility, and integrity, in exploration, engineering design, construction estimating, and project construction, will be examined. It is suggested that anticipated geotechnical conditions be defined unconditionally. The alternative choice is to give the bidder the opportunity of making the interpretive judgements based on geotechnical data. Similarly, a unilateral method of establishing encountered conditions that are agreeable to both owner and contractor, must be outlined prior to contracting. As anticipated and encountered conditions are firmly and accurately established, significant differences can evaluated based upon limitations specified in the contract documents. Impact of differences on project costs can be fixed by pre-defined methods.

Jan 1, 1983

By T. Seal

Hydro-Jex© releaching was undertaken during the summer of 2010 at the Valley Leach Facility (VLF) at AngloGold Ashanti?s Cripple Creek & Victor Gold Mine. Several advancements to the technique were made in response to the technical design and operational challenges posed by the unique site conditions. New geophysical resistivity monitoring techniques were developed to monitor solution migration during the injections. These developments are presented along with discussion of gold production resulting from the project.

Jan 1, 2011

By Poltak Sinaga

PT Kaltim Prima Coal?s 13.1 km overland conveyor (OLC) was commissioned in 1991. It is of conventional 3 roller 350 trough belt type. Cost and performance optimization during initial design ended up with 5.4 mps belt speed, 1000 mm belt width to convey 1350tph, and 7 mtpa of coal. Despite high initial figure, the belt speed was lifted to 6.5 mps in 1996 to accommodate mine throughput increase. In 2002, new low loss ST2100 1100mm wide belt replaced the old ST2250 due for change-out. An upgrade project was initiated at the end of 2003 to further increase the belt speed to 8.5 mps, hence to increase the OLC capacity to 30 mtpa (million ton per annum). Performance data, experience of site personnel, site observation and tests, benchmarking, and information from equipment manufacturers were major inputs to the design review. The project fast track was another challenge in addition to executing modifications on a production lifeline. The project was completed within fifteen months and the OLC was successfully commissioned at 8.5 mps belt speed in February 2005. The OLC has been to date conveying 4 200 tph satisfactorily.

Jan 1, 2008

By R. Barthel, O. Nitzsche, J. Pateiro Fernández, T. Cramer

The Hong Gai coal field in northeast Vietnam has been the main coal mining area of Vietnam for more than 150 years. Anthracite coal is produced from several open pit and underground mines situated close to the UNESCO world natural heritage site Ha Long Bay. The mining-induced environmental impacts such as dust emissions, acid mine drainage, and visual impairments due to waste dumps resulted in severe conflicts of interests regarding future land use and the protection of the world natural heritage site Ha Long Bay. Within the RAME project (Research Association Mining and Environment in Vietnam), Brenk Systemplanung is contributing to an improved environmental and sustainable planning in Vietnam's mining industry and the reduction of environmental impacts on Ha Long Bay by developing suitable and sustainable technology and planning measures (e.g. for dump construction/rehabilitation, predictive modelling, and/or monitoring) for Vietnam's leading coal producer.

Jan 1, 2011

Using mines in Canada, Boart Longyear, a leading provider of drilling services and products, has put its Stage 3 Coring Bit to the test and each time the bit has passed the test with great success. After more than a year in the field at a major mine operation in Sudbury, Canada, the Stage3 coring bit broke life records to become recognized as the most productive design in the industry. In addition to the proven advantage seen in regular bit life increases of as much as 300 percent in some cases, the design is quickly being recognized for its cost-saving operational impact. In Sudbury, the mine operation realized actual cash savings of more than C$45,000 within an eight-month period by making the switch to Stage3 bits. For years, the Sudbury Basin team has relied on the Alpha Extended Crown bit with the Express Waterway geometry option, ordering approximately 500 units per year. This 07 COM ECEX configuration performed well in medium-hard, non-abrasive to ultra-hard, non-abrasive formations with an average bit life of 150 m (490 ft). While satisfied with the performance of the Alpha Ex-tended Crown, the team agreed to put the new Alpha Stage3 to the test. Boart Longyear?s field engineers supplied five drill sites with Alpha Stage3 bits in a 07 COM configuration. After thoroughly testing the Stage3, the results were clear. Even with the well-known performance and versatility offered by the previously preferred configuration, the Stage3 set a new standard of bit performance. The new bit maintained its cutting edge for up to three times longer than the Alpha Extended Crown, a significant performance increase when compared to the 07 COM ECEX.

Jan 1, 2009

By Z. T. Bieniawski, E. H. Skinner, R. A. Cummings, F. S. Kendorski

INTRODUCTION Caving Mine Drift Support Design The support of production drifts remains a high-cost item facing the developer or operator of an underground caving mine. Support costs are incurred well in advance of ore production, and there is a strong need to minimize these pre-production commitments of capital. Due to the extensive rock loads that normally develop during the caving process, the support used in caving mines is typically quite heavy and therefore costly. The process of designing this support increasingly makes use of basic tunneling principles, but is hindered by the still-incomplete state of knowledge of rock behavior in caving mines, and high variability of geological conditions in caving orebodies. Caving mines differ from tunnels in that the deformations and rock loads induced are transient and dynamic in occurrence, and are normally large in magnitude, often well in excess of rock mass strength. As opposed to tunnels, caving mine layouts are more intricate, and the methods and effects of construction ordinarily are not as closely monitored. Safety factors in mining tend to be lower and rock masses tend to he weaker. These aspects prevent strict application of tunnel design technology to caving mine drift support, with the result that mine drift supports are commonly designed chiefly on the basis of experience at other mines. Mining procedures at caving mines are evolved in response to site-specific requirements, to the extent that there are really as many caving methods as there are caving mines.

Jan 1, 1983