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By Brad Murray

Evaluating the performance of a shielded tunnel boring machine (TBM) can be difficult because the ground cannot be observed directly and in relation to the TBM attitude within the excavation. It is difficult to determine whether performance problems are caused by ground loading, steering issues, fine muck packing against the shield, or migration of annular grout around the shield. The Arrowhead Tunnels Project in Southern California uses strain gauges on its shielded hard rock TBMs to detect shield strains early and correlate them with tunneling conditions, thereby increasing the chances that problems will be correctly diagnosed and addressed to optimize TBM performance. The frequent automatic measurement of shield strain has also been valuable by confirming whether remedial methods used to free the machine after stoppages are effective. This paper discusses the qualitative interpretation of characteristic strain patterns on the Arrowhead Tunnels TBM shields and discusses installation details and special considerations for setting up a strain measurement system.

Jan 1, 2008

By Lawrence Y. Marks

During the mineral survey of the Bob Marshall Wilderness and study areas by the author in 1971, 1973, 1974, and 1976 (Marks, 1978), the area designated Reservoir-North (RARE II No. H1-485) in January, 1979, (U.S. Forest Service, 1979) was examined, along with other lands adjacent to the earlier study areas. However, the 1978 open-file report covered only areas originally designated for study. The present report on Reservoir-North is based on earlier work. No work has been done in the area since 1976. Mineral Appraisal Reservoir-North RARE II area (No. H1-485) is in the Northern Disturbed Belt which has been identified as having high potential for natural gas accumulations and lesser potential for oil accumulations (Mudge, 1978). Oil and gas lease applications in the area, indicate interest by oil companies.

Jan 1, 1981

By Kevin Beirne

Most people involved in the mining industry are familiar with student-industry co-op work-study programs. Many colleges and universities have used them for years. Northern College’s Haileybury School of Mines student co-op program adds a new dimension of productivity to the college and the mining industry. The college is located in Hailey-bury, Ontario, Canada. An example of the program’s success is the school’s relationship with Sabin Metal’s SMC (Canada) Ltd.’s McAlpine Mill in Cobalt, Ontario. Students gain practical knowledge and experience while industry gains an eager-to-learn worker. And many of the college’s advanced research services are made available to industry to supplement their own capabilities. The McAlpine Mill was established to provide custom milling of slags and ores. It also recovers metal values from other products of the primary and secondary precious metal industries.

Jan 1, 1999

By Michael Alber

Coal mining by the longwall method typically causes seismic events. This paper describes the research on mining induced seismicity around two specific longwalls at 1100m depth under several old longwalls. A local network featuring 21 geophones has been installed, underground core drilling and an extensive rock testing program were executed. A rock mechanical model featuring a multi-layer strata was created for use with numerical analyses. Seismic events were localized and three different event types are described. Focal analyses yielded distinct modes of failure. Those types are explained by different failure mechanisms, namely fault activation, remnant pillar punching and beam failure. The use of rock mass classification, rock mass strength criteria and in situ stresses together with 2D and 3D numerical analyses allows evaluating the findings from seismology approaches. Conclusions are drawn that the orientation of longwall with respect to the major horizontal stress orientation plays an important role in mine induced seismicity.

Jan 1, 2008

By J. L. Gillson

Joseph H. Birman (Chairman, Dept. of Geolcgy, Occidental College, Los Angeles, Calif.) Many thanks to J. L. Gillson for so comprehensive a survey of the titanium sand deposits of the world. Over the past two years, the writer studied rather carefully some of the Cretaceous ilmenite deposits in New Mexico and Colorado, including the Sanostee deposit shown in Gillson' s map, Fig. 6. The deposits were geologically mapped and sampled, surveyed by magnetometer, and the Sanostee deposit was drilled. Moat of the genetic interpretations made by Gillson concerning the recent sedimentary ilmenites can be clearly read in the Cre-taceous deposits in New Mexico. The deposits are in marine regressive members of the Mesaverde group. The deposits trend within a few degrees of N 55° W and persistence of this trend through both distance and time (the deposits are in different members of the Mesaverde group) implies that the deposits are offshore bar accumulations. Heavy mineral content ranges from about 10 pct to more than 50 pet. Thicknesses are from 4 ft to as much as 20 ft, widths range from 150 to 600 ft, and lengths range from a few thousand feet to a few miles. All are locally or completely overlain by carbonaceous shale and thin coal. The deposits are strongly altered, and from X-ray diffraction the principal titanium alteration product appears to be anatase. Drilling of the Sanostee deposit shows that the alteration is not related to the present erosion surface but took place at the site of deposition and before burial by the overlying sediments. Iron oxide derived from the alteration cements the grains and is the chief coloring agent in the immediately overlying shales. In the Sanostee deposit, there is virtually no feldspar, the gangue mineral being almost exclusively quartz. Sorting is excellent, but the quartz grains are subangular to angular. Petrographic examination reveals that the angularity is not due to overgrowths. Therefore, short distance transport is implied. The mineralogical composition suggests a low relief granitic terrane as the source area. Feldspar may have been decomposed by weathering at the source, but an alternative preferred by the writer is that each of the deposits represents a long-term concentration site (for example a large sand bar) which was continually being deprived of light minerals by wave action and selective transport. Feldspar may have been mechanically reduced in size more quickly than the quartz, and thus its rate of removal may have exceeded that of quartz. Concentration of heavy minerals would thus occur until the marine regression removed the zone of maximum wave energy from the site. Chemical alteration would then become the most important process until burial by encroaching swamp deposits.

Jan 1, 1961

By D. Marotte, M. David

"A new exploration procedure is proposed for volcanogenic massive sulphide deposits of the Abitibi belt. ""Samples"" of acidic volcanic rocks (Si02 > 60%) were compiled from the literature. From the 574 samples collected, 322 were used in each of a number of experiments. Forward inclusion linear discriminant analysis performed on the untransformed geochemical data shows a general depletion in Na20 and CaO along with an enrichment in MgO for a ""proximal"" group of samples relative to a ""distal"" one. The percentage of misclassified samples reaches 20% to 30%, but test sets shows good stability.The exploration procedure was applied to the Normetal deposit, where the authors took 160 samples during the summer of 1977. It quickly leads to the definition of targets for more detailed exploration together with a good recognition of the old known deposit.IntroductionVolcanogenic massive sulphide deposits in the Abitibi belt (Quebec) are mainly found in rhyolites or acidic pyroclastics in the uppermost portion of a calc-alkaline volcanic series (Descarreaux, 1972). The deposits are thought to have formed syngenetically by the action of volcanic hydrothermal exhalations during the waning episode of a felsic volcanic cycle (De Rosen Spence, 1976). Alteration pipes of disseminated sulphides are commonly present. Metal deposition from hot springs, initiating convection cells in a submarine environment, may have been the dominant process in ore formation (De Rosen Spence, 1976)."

Jan 1, 1981

By Barrick Pierina, John Frostiak, Igor Gonzales, Kenneth G. Thomas, Ken Manning

"1.0 SummaryThe Pierina deposit was acquired in August 1996 when Barrick Gold Corporation purchased Arequipa Resources, a junior mining company with extensive land positions in Peru. At the time of acquisition, Arequipa had developed two exploration tunnels and drilled 9 exploration holes on the property. Metallurgical tests, conducted on samples taken from the tunnels and the exploration holes indicated that the ore was amenable to heap leaching. Barrick’s exploration team recognised from the outset, the potential of the mineralisation and convinced Barrick’s senior management that this was indeed a world class deposit that should be pursued. On November 25, 1998, the first dore was poured at Pierina, 27 months from the time of acquisition. During that period Barrick completed its exploration programme, prepared a development plan including capital and operating costs, production profiles and cash flow forecasts, and a schedule to develop a mine and construct a leach pad and gold recovery plant, including all supporting infrastructure. All permits and environmental approvals were obtained and all necessary land was acquired. The project was completed on schedule and under budget. This was the first greenfield mine development for Barrick outside of North America.This paper details, mainly, the research and development, engineering, construction and commissioning of the metallurgical process facilities.2.0 The Develonment ProgrammeImmediately after the acquisition, Barrick began the process of gathering information required to prepare a project development plan. Kilborn Engineering was retained to assemble all of the information collected and collated into a development plan document. This document was completed by June 16,1997. The objective was to bring the mine into production as quickly as possible with critical activities identified as follows:"

Jan 1, 2000

By J. T. Peters, N. Schapiro, R. J. Gray

Petrographic studies of coal have resulted in a better understanding of the origin and composition of coal and have added to the knowledge of how and why coals differ in their response to various prepamtion and utilization processes. Petrographic methods can now be used in scientific economic exploitation of coals. Because the United States Steel Corp. is one of the largest consumers of coal and coke, there is a continuing interest in the corporation in perfecting a better understanding of coal so that it can be utilized more effectively. Coal is a heterogeneous substance composed principally of plant material that has been altered by a complex geochemical process to form rock. The science of coal is anthracology. The ultimate aim of anthracology is determining the relationships and differences among coals. The fundamental aim is finding out why coals differ. The practical application is determining how the differences in coals affect their utilization properties. Coal, like other sedimentary rocks, consists of more than one material. Fig. 1, a photograph of a natural fracture and a polished surface of a lump of coal, displays heterogeneity in terms of the banded ingredients present. The earliest attempts to describe coal were based on its hardness and appearance. ' Thus, coal has been described as hard or soft, bright or dull, and banded or nonbanded. The variations in the hardness and physical appearance of the coal reflect differences in materials that constitute the coal. The banded nature, lustre, and texture depend upon the relative proportions of the various constituent materials. Even the earliest petrographic investigations of coal produced evidence of of the heterogeneity of the coal substance and shoul have destroyed the concept of the unit coal molecule. Coals (Fig. 2) that appear the same frequently consist of different microscopic materials and may behave differently during mining, pulverization, washing, or coking. In Fig. 3, the upper photograph shows a bright at-trital medium-volatile coal, and the micrograph at the right shows some of the materials that constitute the coal. The lower photograph shows a bright attrital low-volatile coal and the corresponding micrograph shows material of similar origin to those from the medium-volatile coal. Any petrographic description of a coal that has meaning in terms of its utilization begins with a microscopic examination. Numerous attempts have been made to describe coal on the basis of the materials that constitute the coal.2*3 Initial petrographic studies were directed towards the question of the origin of coals without any true basis for studying the metamorphic changes in the

Jan 1, 1962

The pellet plant, built by Dravo Corp, in Groveland, Mich., for the Hanna Mining Co., is now in full operation. Although using jasper, a type of iron ore with low iron content (approximately 28% Fe), the plant has a rated capacity of 1,250,000 tans of pellets per year. In its four years of existence, the nearby concentrating plant has seen its capacity increase from 700,000 tons to 1,500,000 tons a year as part of a major expansion program at Groveland. Utilizing the Dravo-Lurgi continuous grate process, the pellet plant produces %a-in. pellets of more than 60% iron content. The fully-hooded pelletizing grate, largest in the U.S., is 9 ft. 10% in. wide and 223 ft. 1% in. tong over 34 windboxes, with an effective hearth area of 2195 sq. ft. Drying, firing, and cooling functions are all carried out on this single piece of equipment.

Jan 4, 1964

By Donald Leroux

For the last few years, the grinding model first proposed by Andrews and Mika (1975) has regained attention from the scientific community. Though sophisticated identification algorithms have been developed, the number of its parameters that have to be estimated remains huge. Most of these constants (often more than 90%) are for the breakage function. This paper describes a new method for reducing efficiently the number of the breakage function parameters of the Andrews-Mika grinding model. It makes use of second-order statistics and of a stereostochastic model for liberation (for instance, BooKing).

Jan 1, 1992

By James R. Boyle

The value of Alabama's nonfuel mineral production in 1984 was $409.8 million, and established a new record high for value of nonfuel minerals in the State, at 13.4:% over the previous high of 1983. Output of nearly all nonfuel minerals increased; phosphate rock was one of the exceptions, with no recorded output in 1984. Cement, crushed stone, lime, sand and gravel, and clays were the major commodities produced in Alabama. Alabama led the Nation in the production of crushed marble; was second in bauxite; third in fire clay and kaolin; fourth in bentonite, ferroalloys, and dimension marble; fifth in masonry cement, lime, and recovered sulfur; and sixth in portland cement. Alabama ranked 22d in the Nation in value of nonfuel minerals produced.

Jan 1, 1986

With some notable exceptions, marine placers located just below, or just above, present sea level, are responsible for much of today's production of detrital ilmenite, rutile, zircon, and other minerals of value. The purpose of this paper is to discuss the paleogeographic and paleo-oceanographic factors which may have determined the location of presently submerged marine placers. These factors include changes in sea level, burial by recent marine sediments, stream capture and other changes in drainage patterns, and recent changes in climate. Selected geologic situations in the Yellow Sea off the coast of Korea, in the Atlantic Ocean off the coast of Portugal, in the Bering Sea off the coast of Alaska, and in the Arabian Sea off the coast of India, will be used to illustrate the author's point of view.

Jan 1, 1971

By Gary Jackson

Preliminary engineering for the Waller Creek Tunnel was completed in 2001, but the project was held in abeyance until the summer of 2007. This paper describes several features of the revised design, which required significant changes from the original concept. Most notable is the expected replacement of a tunnel boring machine (TBM) by conventional tunneling. The considerable influence of geological conditions on the tunnel vertical alignment is discussed, in particular the impact of the zones of Eagle Ford Shale with swelling potential. Other features which are described include the wide span tunnels and large diameter shaft requirements.

By Harry R. Price, Jerome C. Neyer

INTRODUCTION Safety must be a primary consideration in the design and construction of tunnels. Tunnel construction has historically been considered a high-risk business. During the construction of the 14.8 kilometer (9.25) mile St. Gotthard Tunnel in the Swiss Alps in the 1870s, 310 lives were lost and another 877 workers permanently disabled. In more recent days, two tunnel construction accidents in 1971, one in Michigan and one in California, claimed the lives of 38 workers. Prior to 1971, most regulations governing safety in tunnel construction were developed by the U.S. Bureau of Mines. These included a 1941 Bulletin 439, "Some Essential Safety Factors for Tunneling" and a 1968 Bulletin 644 which updated Bulletin 439. In 1970, the United States passed the Occupational Health and Safety Act (OSHA) which became effective in early 1971. That act covered all sorts of workplace activities including Tunnels and Shafts in 29 CFR 1926.800. In 1989, a revised and renamed 29 CFR 1926.800 was issued for Underground Construction. Some of the changes introduced in this rule were the outgrowth of improvements made in the California and Michigan codes after the 1971 accidents. These new regulations are the "Rules to Live By" for tunnel construction in the United States and are generally accepted as appropriate for tunnel construction throughout the world.

Jan 1, 1995

By Y. A. Rocher, J. E. Dorn, L. A. Shepard

Creep activation energies for single aluminum crystals favorably oriented for shear by (010) [101] glide were detemined over the temperature range from 78" to 900°K. Observations of slip bands on the specimen surface were made in conjunction with the investigation. From 78" to 780°K, the activation energies obtained in this imestigation agreed closely with those previously found for creep by (111) [101] slip. Between 78" and 140°K, the activation energy was identified with the Peierls process, while between 260°and 780°K the activation energy was close to that for cross-slip. The coarse wavy slip bands nominally parallel to the (010) plane observed above 260°K were attributed to fine cross-slip. From 800" to 900°K, unusually high apparent activation energies ranging from 28,000 to 54,000 cal per mole were obtained. These apparent activation energies were attributed to re crystallization. AS illustrated in Fig. 1, a recent investigation1 has shown that creep of aluminum single crystals by the (111) [i01] mechanism is controlled by three unique processes, each of which is characterized by a single activation energy which is independent of the applied stress and the creep strain. A comparison of the observed activation energies with theoretically calculated values permits a fairly clear identification of the three operative creep processes. Below 450°K, where the activation energy for creep is 3,400 cal per mole, the deformation is controlled by the Peierls process, the activation energy for creep agreeing well with that calculated by seeger2 for the energy required to nucleate the motion of a dislocation loop against the atomic forces of the lattice. Between 590° and 750°K, the observed activation energy for creep of about 28,000 cal per mole agrees well with the energy necessary to induce cross-slip. Seeger and schoeck3 estimate that the activation energy is about 24,000 cal per mole whereas Friedel4 recently calculated this activation energy to be 28,000 cal per mole. Above 800°K the activation energy of 35,500 cal per mole that was observed for creep agrees well with that estimated for self-diffusion in aluminum.= In this range the operative rate-controlling slip process has been clearly identified as that arising from the climb of edge dislocations. The objective of this investigation is to ascertain whether a single crystal of aluminum favorably oriented for simple shear in the [loll direction on the (010) plane might exhibit uniquely different activation energies for creep from those obtained previously for (111) [101] slip. Whereas the exis- tence of such unique activation energies would constitute incontrover table evidence for new mechanisms of slip, the absence of any new activation energies might suggest that slip of aluminum is confined to the (111) [loll mechanism. Several factors prompted the selection of the (010) [101] orientation for study. First, there are more reported observations of (010) [loll slip than of any other nonoctahe-dral mechanism.8-10Secondly, Chalmers and Martius1l have concluded from considerations of the energies of dislocations that (010) slip is the second most favored mechanism in face-centered-cubic metals. Finally, favorable orientations for simple shear by the (010) [loll mechanism provide the least favored orientation for slip by the (111) [101] mechanism. EXPE-RIMENTAL PRO-CEDURE The high-purity aluminum stock, specimen preparation, shear fixture, extensometry, and experimental technique used in this investigation were the same as those previously reported.' Single-crystal spheres grown from the melt of 99.995 pct pure Al* were _ *The high-purity aluminum used in this investigation was graciously given by the Aluminum Company of America. oriented, carefully machined into dumbbell-shaped shear specimens, annealed, and chemically polished. The finished specimen had a central reduced section 0.190 in. wide and 0.590 in. in diam and 1/4-in. grip sections at both sides, 0.690 in. in diameter. The specimen was oriented in the stainless steel grips of the shear fixture with the (010) plane perpendicular to the dumbbell axis and the [loll direction parallel to the stress axis within 2 deg. Creep activation energies were calculated in the previously described manner1 from determinations of the instantaneous change in shear strain rate produced by an abrupt 15 to 20 deg increase or decrease in test temperature. If is the instantaneous strain rate at strain y and temperature T1, and ?2 the instantaneous rate at y and T2,

Jan 1, 1960

In his account of the Thackaringa sulphide ore, Lawrence (p. 92) reports the presence of valleriite as a minor accessory in chalcopyrite. He says that it is readily identified by its intensive anisotrophy and reflection pleochroism. He also gives (p. 87) the chemical formula as Cu8Fe4S7 Recent work by Evans et al. (1964), Chamberlain and Delabio (1965), and Schidlowski and Otteman (1966) suggests that most material identified as valleriite is, in fact, mackinawite. Mackinawite and valleriite are both extremely anisotropic and strongly reflection pleochroic, and so with fine-grained material it would be hard to distinguish them optically.Mackinawite, according to Evans et al. (p. D66) is a copper-free iron sulphide (PeS) with small quantities of nickel, whereas valleriite is considered to be a dimorph of chalcopyrite (CuPeS2 ). They found that mackinawite is much more widespread than valleriite, and, unlike the latter mineral, is commonly included in other sulphides, particularly chalcopyrite.Lawrence (p. 92) states that the valleriite inclusions are up to 0·01 mm long, so that an electron probe microanalysis should be quite feasible and provide a ready answer to this query.L. J. Lawrence: I thank Dr Townend for his comments on the occurrence of a valleriite-like mineral embedded in chalcopyrite from Thackaringa. The problem of distinguishing valleriite from mackina...

Jan 1, 1967

By Alan A. Campoli

The U.S. Bureau of Mines evaluated two different conventionallongwall gate entry systems in the Southern Appalachian Basin, where mining and geologic conditions are conducive for coal pillar bumps. These gate entry systems were in a coal mine located in the Pocahontas No.3 Coalbed under approximately 2,000 ft of overburden and a massive quartzite sandstone member, and both employed a center abutment pillar flanked by yield pillars. The 8O-ft-square tailgate abutment pillars within the first study area began bumping 500 ft in advance of mining. This was accompanied by face bumps on the tailgate corner of the longwall face. The 120-by 180-ft tailgate abutment pillars within the second study area did not begin to bump until mining was approximately 100 ft past. Coalbed stress change and abutment pillar dilation data demonstrated that a 15-ft-wide perimeter of yielded coal surrounded a highly stressed core in both sizes of abutment pillars. The 62 pet more core area per foot of gate entry in the larger abutment pillars prevented excessive load transfer to the corner of the tailgate panel and eliminated the face bumps experienced with the original gate entry design.

Jan 1, 1990

By E. Sun

Tailings disposal is a significant consideration for the mining industry, with the majority of the ore processed in most mining operations ending up as tailings. Several tailings dam failure accidents have occurred during the past few years and mine tailings dam failures are occurring at relatively high rates. Tailings dam failure is disastrous with the serious damage and the loss of lives. To increase the tailings dam safety, a tailings dam monitoring and pre-alarm system (TDMPAS) based on the internet of things and cloud computing platform has been accomplished with the abilities of real-time monitoring of the saturated line, impounded water level, rain fall and the dam deformations etc. The TDMPAS has been applied in several mines in China and helped the mine engineers monitor the tailings dam safety and get warning information automatically and remotely in any kind of weather conditions. This work has been demonstrated the tailings dam monitoring and pre-alarm system (TDMPAS) is meaningful to monitor the tailings dam physical safety condition. The TDMPAS could be applied to monitor all the national tailings dams online in the future.

Jan 1, 2012

By J. L. Cupp, R. C. Ford, B. R. Romig

The Climax Molybdenum Mine, located near Leadville, Colorado, is the site of a lengthy mining history spanning more than 80 years. In the 1960’s, extraction of molybdenum from oxide ore located adjacent to the massive molybdenite sulfide deposit resulted in the construction of an earthen core dam to impound fine-grained oxide tailing in the Eagle River Valley. Through recognized value of water storage and reclamation opportunities, a tailing removal project was initiated in 1993 to convert the impoundment facilities to a post-mining beneficial land use of developed water resources. An evaluation of the effect residual materials and lake dynamics would have on in-stream water quality was performed. Eagle Park Reservoir stands as a model for future reclamation efforts that involve water delivery to highly sensitive receiving waters. This paper provides a case study on project development, the evolution of water quality assessment, and the regulatory framework that contributed to this project’s success.

Jan 1, 1999

By Mohammad Irshad, Klaus Mussger, Harald Wagner

Despite the fact that the New Austrian Tunneling Method; NATM, has been used in the United States for the past 23 years or so, still considerable misconceptions exist in the industry about the nature of the method and its implementation. In the authors’ view its implications are usually not well understood. The paper provides an overview of the highlights of NATM usage over the past two decades to illustrate the point that NATM is now a well-established tunneling method in the U.S.A. Accordingly the thrust of this paper is on the more pragmatic aspects of the NATM technology usage as it concerns the Owners, Designers and the Contractors. Prior to examining the implications of NATM usage from the viewpoints of various stakeholders, it should be helpful to first briefly provide an overview of the history of the method as it was introduced and implemented on several key tunneling projects in the US, over the last 2 plus decades.

Jan 1, 2005