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By V. McLemore, A. Fakhimi, K. Donahue, D. Sweeney, V. Viterbo

In order to evaluate the relationships between weathering and durability and strength of rock samples from the Goathill North rock pile at the Molycorp Questa mine, NM, we conducted slake durability and point load tests. Slake durability index (ID2) values ranged from 84 to 98%. Point load strength index (Is50) averaged for all rock units ranged from 1.1 to 5.7 MPa. Results show a slight positive trend between ID2 and paste pH. Two populations of data are distinguishable when ID2 is plotted versus the percentages of chlorite, illite and internal friction angle. In general, Is50 values increase toward the interior of the rock pile. Preliminary conclusions indicate that the durability and strength of the rock pile material generally increase toward the interior of the rock pile. Pre-rock pile alteration and post-rock pile weathering history have affected the durability of the GHN rock pile samples.

Jan 1, 2007

By J. L. Carr

Continuous mining machines are extensively used in the underground coal mining industry. These machines are typically remote-controlled, and severe injuries and fatalities occur every year when a miner is struck or pinned by the machine. Proximity detection systems offer a means to prevent these types of injuries and fatalities by sensing the presence of a miner and disabling machine motion. Researchers at the National Institute for Occupational Safety and Health (NIOSH)have developed the Intelligent Proximity Detection (iPD) system to provide enhanced protection while minimizing false alarms. The iPD system uses a set of pre-defined rules to determine which machine motions are safe and which would present a potential hazard, and automatically disables only the potentially hazardous motions. This system has been installed and tested on a Joy 14CM continuous mining machine at the NIOSH Office of Mine Safety and Health Research in Pittsburgh. Under laboratory conditions, the achievable accuracy and performance of the iPD system has been quantified with respect to a number of variables including position of the conveyor boom, presence of the machine?s trailing cable, and orientation of the miner-wearable component. Disclaimer: The findings and conclusions in this report are those of the author(s) and do not necessarily represent the views of the National Institute for Occupational Safety and Health. Reference to specific brand names does not imply endorsement by the National Institute for Occupational Safety and Health.

Feb 27, 2013

By S. Veeramasuneni, C. D. Dunbar

The rate of hydration influences many important physical properties of gypsum. Previous research examined the rate of gypsum hydration and related this to compressive strength and microstructure development using BET specific surface area analysis. The analysis of gypsum porosity in combination with BET surface area and rate of hydration remains to be done. In the present study, mesoporosity is analyzed using the numerical method of Barrett, Joyner and Halenda (BJH) to gain a greater understanding of gypsum hydration and microstructure development. The rate of hydration has a significant effect on mesoporosity of the gypsum matrix. The results reveal the effect of mesoporosity and hydration rate on some macro physical properties of gypsum.

Jan 1, 2000

By F. M. Doyle, Jun Li, Milton E. Wadsworth, Ximeng Zhu, E. Peters

The electrochemical behavior of pyrite in borate/sulfate solutions was investigated using cyclic voltammetry. Three anodic peaks at approximately -0.8 V, -0.1 V and +0.5 V (SCE) were detected along with their corresponding reduction peaks. The first two peaks correspond to the oxidation of surface products. The third peak corresponds to the direct oxidation of pyrite with reaction products FeO oxides. sulfate ion and partially oxidized sulfur intermediates present as a surface film of polysulfides and So. The Few oxides and sulfur intermediates were reduced to ferrous hydroxide and HS during the negative-going scan. The HS interacted preferentially with Fe(OH), on the surface to form FeS. Excess fenous hydroxide continued to reduce to metallic iron. During the return positive-going scan, metallic iron was oxidized to ferrous hydroxide and FeS was oxidized to pyrite. These reactions are characterized by a unique double peak observed in the region -0.8 to -0.65 V. The growth kinetics of the surface sulfur film formed during anodic oxidation were studied using chronoarnperomeay. Potentiostatic measurements were well correlated by a paralinear rate equation, suggesting the formation of an intermediate passive film, associated with the simultaneous dissolution of the outer layer of the film. The reaction rates were affected by applied potential, solution pH and temperature, but were independent of electrode rotation speed. A reaction kinetics model which fitted well with experimental results, was developed.

Jan 1, 1993

By Paul G. Schmidt

Exxon Minerals Co. was exploring for mineral deposits in Precambrian terranes of the US portion of the Lake Superior region in the late 1960s. Exploration drilling and other activities had been concentrated on massive sulfide prospects in northeastern Minnesota, but general exploration studies and competitor scouting were conducted in other areas of the region. These activities drew attention to Wisconsin in 1969 when it became apparent that Bear Creek Mining Co. had made a discovery near Ladysmith in the northwestern part of the state. Observation of their drill hole pattern suggested that a massive sulfide deposit, since named the Flambeau deposit (Schwenk, 1977), had been found. With this background, Exxon initiated an exploration program for Precambrian massive sulfide deposits in northern Wisconsin in 1970 (Figs. 1 and 2). Northern Wisconsin is extensively mantled by Pleistocene glacial drift and bedrock outcrop is sparse. Other than iron mines in the extensive iron formations along the Wisconsin-Michigan border and Jackson County, no significant mineral deposits were known in the Wisconsin portion of the Precambrian Shield until the discovery of the Flambeau deposit. Until the mid-1970s, the only specific published literature on the Wisconsin Precambrian consisted of old outcrop locations and descriptions in journals of the Wisconsin Geological and Natural History Survey (Chamberlain, 1882; [ ] Weidman, 1907; Hotchkiss, 1915) and the summary maps of Dutton and Bradley (1970).

Jan 1, 1991

By E. Haug, Quamrul Ahsan, R. Norcross

Cyanide leaching is the most common process employed in the majority of the gold extraction plants. These gold extraction plants naturally generate tailings and/or effluents that contain highly toxic cyanides, In geographic locations with excess precipitation and therefore net positive water balance, a portion of these tailings must be discharged. Before these highly toxic cyanide-containing effluents can be discharged to the waterways, cyanide and any other toxic substance must be destroyed. Geographic locations with high evaporation and low precipitation, as in the western USA, result in net negative water balance and therefore these plants can operate with a zero discharge option. However, with the current stringent environ­mental regulations and concerns for bird and wildlife mortality, even these operations may be required to partially treat their tailings to preclude potential harm to wildlife. Furthermore, heap leach opera­tions are now generally required to detoxify the heaps before abandonment. It is, there­fore, apparent that all gold extraction plants may be required to install some form of effluent treatment in order to achieve the above objectives,.

Jan 1, 1990

By George McArthur

GEOLOGY One of the largest copper resources in North America occurs in the Bingham mining district, located 40 km (25 miles) southwest of Salt Lake City, UT. Anaconda's present contribution to the development of this resource is the Carr Fork mine. (Fig. 1, Bingham district plan map.) The Carr Fork story began about 300 million years ago when a thick sequence of sedimentary quartzite and limestone was deposited in the Oquirrh Basin. Subsequent earth stresses formed a series of west-northwest-trending overturned anticlines and synclines that were later offset by northwest-striking thrust faults and northeast-trending normal faults. (Fig. 2, Bingham district cross section.) About 38 million years ago the Bingham stock was intruded into some of the folds, resulting in the formation of porphyry ore in the intrusive, and fissure, replacement, and skarn ore deposits in the sediments. The Carr Fork skarns were formed preferentially in two limestone units, called the Yampa and Highland Boy, which average about 46 m (150 ft) in thickness, separated by about 76 m (250 ft) of quartzite. Copper mineralization consists almost entirely of chalcopyrite associated with pyrite and molybdenite in a gangue of garnet, diopside, magnetite, quartz, and carbonate. Molybdenum, gold, and silver are economic byproducts. (Figs. 3 and 4, indicated ore in plan and section.) EXPLORATION HISTORY The West Mountain mining district, of which Carr Fork is a part, was organized in 1863, after leaf-silver ore was discovered in the Carr Fork of Bingham Canyon. However, it was not until 1873, when the Bingham and Camp Floyd railroad to the town of Bingham was completed, that the mining camp flourished. Many small mining companies in the district were reduced, often through consolidation. By 1937 only the National Tunnel and Mines Co. was active in the Carr Fork area. In 1948 it declared bankruptcy, and was later purchased by The Anaconda Co. Anaconda conducted geologic investigations in the Bingham district until 1968, when a concerted diamond drilling program was initiated to fully evaluate the geologic potential of the Carr Fork area. The exploration program commenced with one diamond drill, but was enlarged to three drills following discovery of the first major ore intercept. Near completion of the exploration effort, large oil well rotary drills were used to drill to depths of 762 to 914 m (2500 to 3000 ft), after which the holes were completed by standard diamond drilling techniques. All holes were collared vertically, but considerable deviation occurred because of structure and rock conditions. Wedging and directional drilling were used to keep the holes on target and to provide multiple ore intercepts in the deeper holes. Geophysical surveys, in-

Jan 1, 1982

By Walter C. Labys

This paper reports on recent modeling efforts to analyze the eastern U.S. steam coal market with a cross-sectional econometric as well as a quadratic programming approach. The background to coal modeling is examined first. The particular aspect of the steam coal market to be modeled are then presented and the corresponding coal model described. Both empirical results and rigorous mathematic pertubation analysis are presented. Conclusions are then drawn regarding potential modeling applications in the policy area.

Jan 1, 1979

Maptek I-Site laser scanning expertise and software technology is being used to map the geology and layout of the deepest underground laboratory to be established in the U.S. The Deep Underground Science and Engineering Lab (DUSEL) in the former Homestake gold mine in Lead, SD, will provide for scientific studies in particle and nuclear physics, geology, hydrology, geo-engineering, biology and biochemistry. The project, funded by the National Science Foun¬dation (NSF), will allow geoscientists and engineers to research the behavior of subsurface rock, minerals, water and energy sources

Jan 1, 2010

By Sidney A. Hiscock

INTRODUCTION Lead and zinc are today rightly regarded as sister metals. Historically, however, they differ markedly with lead being known and in general use as the metal since 3000 BC in several countries which at that time might have been described as mature economies. Zinc was not isolated and recognised as an industrial metal with distinct and valuable properties until about 1700-1800 AD (although it had, of course, been utilised as a constituent of brass for some 2000 years previously). c were well established as industrial metals by the beginning of the 20th century. The present paper briefly reviews the overall growth in world consumption* and changes in the three main areas which today represent the mature economies or industrialised areas, i. e. ,Europe, the United States and Japan. Trends in overall consumption are determined by the demands for the individual uses for lead and zinc. The changes in patterns of use in the industrialised areas - individually and collectively - and reasons for the changes are also considered. LONG TERM TRENDS - 1900-1984 The World Picture Since the beginning of the 20th century the world consumption of lead (3.9 million tonnes in 1984) has grown almost fourfold and that of zinc (4.7 million tonnes in 1984) is almost eleven times greater than it was in 1900. The long-term trend has been one of continuing expansion for both. metals although the pattern has been severely disturbed at certain periods, for example in the years immediately following the two world wars and at times of marked recessions in industrialised areas. Apart from such major setbacks, new levels of consumption have been established regularly every few years. Recently, however, consumption has not really grown and with only a slow and partial recovery in world industrial activity at present, there is no indication that the peak consumptions of 4.2 million tonnes of lead, set in 1979, and 4.8 million tonnes of zinc (1973) will be exceeded in the near future. The growth in world lead and zinc consumption since 1900 is shown in Figure 1 (which includes changes in copper and aluminium for comparison). Overall growth over the period 1900-1984 has been about two percent a year for lead and about three percent for zinc (annual growth for copper has also been about three percent). Increases in tonnage consumption and growth rates by decade for lead and zinc are summarised in Table I. However, the growth rates by decade sometimes conceal very large individual annual increases and decreases. For example, in 1975 lead consumption fell by 13 percent and zinc consumption by 22 percent compared to 1974. In 1976 consumption of lead and zinc rose by 12 percent and 18 percent respectively. The years when consumption 'landmarks' (ie one, two, three and four million tonnes) were first reached are shown on Table 2. Clearly, the pattern of shorter periods being required to attain each extra million tonnes of consumption was broken in the 1970's. The consumption of zinc overtook that of lead for the first time in 1940, and since 1946 has always been at a higher level. Trends in industrialised areas The two key industrialised areas at the beginning of the 20th century were Europe and the United States which between them accounted for some 95 percent of world lead consumption and 98 percent of zinc consumption. Figures 2 and 3 show the growth in lead and zinc consumption, and Figures 4 and 5 the percentage shares for each area since 1900. Europe has usually been the major user of lead except for some years in the 1920fs, most of the 40's and early 50's when consumption in the United States was larger. In 1900, Europe accounted for about 64 percent of world lead consumption and the United States just over 30 percent. Currently, Europe takes about 40 percent of world consumption and the

Jan 1, 1986

By Jack Parker

Critical width Before we go further into pillar design, we should look into the matter of "critical width," because of its effect on pillar behavior. Critical width refers to the greatest width that the rocks above the mine can span before failure or, if there are pillars, the width to which we must mine before the pillars accept the full weight of the overlying materials. There are theories to help calculate that probable width, and they usually boil down to one-quarter or one-third of the depth of cover; but they don't always fit, and it would be better for us to understand the factors that control local conditions. Critical width may be controlled by the thickness or strength of one or more of the strata above the mining horizon. In a gold mine, we might have a thick granite or basalt above us, perhaps capable of bridging across most or even all of a small ore body. In that case, pillars might have to support nothing, or perhaps just the weaker or damaged rock below the strong main roof. Obviously it would be wrong to design for tributary load on pillars based on some lab-determined rock strength. In some coal mining districts in Utah, huge steps can be seen in the mountain sides, with slopes on weathered shales and vertical cliffs 100 or 200 ft high in thick, hard sandstones. The sandstones are capable of bridging across hundreds of feet, often making mining deceptively easy at first, but it becomes more difficult as greater areas are opened. Sometimes such a mining sequence leads to violent bumps and bursts as the wide spans of sandstone sag and bear down on the working faces, like giant nutcrackers, or as bridges eventually fail, releasing much pent-up energy.

Jan 1, 1993

By SH. Shahsavari, H. Akbari, M. Noaparast, M. Oliazadeh

Mejel valley zircon ore in Iran is located in north part of Iran and was sampled to evaluate its concentration. The aim of this project was to define the mineralogy of this zone and separating zircon from other minerals using gravity concentrators and magnetic separators. It is constituted of various valuable minerals, mainly zirconium, niobium-tantalum, titanium, rare earth elements particularly cerium-bearing minerals namely zircon, sphene and rare earth elements oxides. We used statistical method for designing of experiments. Yates method used for analysis of basic experiments results. The grade of zircon in primary sample was 1.1%. Different experiments were designed to optimize all required parameters. The final concentration with 75% zircon was produced and final recovery was 79%. Finally, lab-scale based flow sheet was prepared using experiments results.

Jan 1, 2005

By J. A. Organiscak

Two types of airflow splitting methods for improving longwall dust control were investigated by the National Institute for Occupational Safety and Health's Pittsburgh Research Laboratory. Investigated were a translucent mesh barrier and a staged spray barrier system to confine the shearer-generated dust to the coal-extraction side of the longwall face while maintaining a cleaner split of airflow on the opposing worker walkway side of the longwall face. In laboratory experiments and in a longwall field evaluation, the translucent mesh barrier was shown to provide notable dust-control effectiveness for a distance of up to 60 m downstream of the shearer, provided that the mesh barrier remained relatively parallel to the airflow. The staged spray barrier system showed marginal dust-control effectiveness in the laboratory and, therefore, was not field tested.

Jan 1, 2000

By A. Iordanidis

Ieropigi Fe-Ni deposit is located in northern Greece, in Kastoria?s prefecture near Albania?s borders. A laterite profile exposed by opencast mining and placed near the basement of the mine was chosen for sampling. Ten samples, representing ?pure? Fe-Ni ore, ophiolite-bedrock, ?red? ophiolite and ?enriched? ophiolite were collected, based on macroscopic observation. The samples were analysed by X-Ray powder Diffraction (XRD) for the determination of the mineral phases. Iron and Nickel concentrations of the same samples were also determined by X-Ray Fluorescence (XRF) methodology. The Fe-Ni ore samples consists predomi-nantly of hematite, goethite, chrysotile (serpentine), saponite and quartz. ?Red? ophiolite samples consists mainly of chrysotile, hematite, quartz, calcite and small amounts of paragonite and goethite. Bedrock and ?enriched ophiolite samples are comprised of chrysotile, hematite, calcite, quartz, nontronite, paragonite and sepiolite. The Fe content ranges between 13% and 49% in Fe-Ni ore samples and between 7% and 10% in ophiolite samples. The Ni content ranges between 1% and 3% in Fe-Ni ore samples and between 0.3% and 4.5% in ophiolite samples (the higher content is observed in the so-called ?enriched? ophiolite). A correlation between Fe-Ni concentrations and mineral assemblages is being attempted in order to evaluate the nickel-rich mineral phases. It is shown that the nickeliferous minerals are serpentine, hematite, goethite and saponite.

Jan 1, 2006

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 David A. Rice, Scott A. Shuey, William K. Tolley

The U.S. Bureau of Mines (USBM) is developing new dewatering technology to permit the recycling of iron values contained in wet steel plant sludges. In laboratory tests, Q-BOP fume sludge was dewatered to 12% moisture by displacing water with acetone in a plate-and-frame pressure filter. Acetone is reclaimed through distillation at lower cost than conventional thermal drying of the sludge. The projected additional energy requirement for acetone treatment of the sludge, including acetone recovery, is $5 to $7 per dry ton.

Jan 1, 1995

By S. Culp, P. Metcalfe

Web technologies and the Internet have revolutionized the computer industry. The Web browser technologies have also moved to portable devices such as Personal Digital Assistants (PDAs) and mobile phones. This paper looks at how to implement a Web Server solution and addresses some of the inherent advantages in the technology. It will also look at some examples of how plant productivity can be managed with a Web Server approach.

Jan 1, 2002

By Steven W. DeCou, Marcus R. Jensen, Stephen Navin

The Lake Mead Intake No. 2 is a project constructed for the Southern Nevada Water Authority which includes a 12-foot diameter lake tap and intake shaft constructed in over 225 feet of water; 1650 feet of 16x14-foot horseshoe-shaped tunnel leading to a forebay that is 165 feet long, 35 feet tall, and 30 feet wide; twenty-two 4-foot diameter steel lined well shafts extending 325 feet from the ground surface to the forebay; 3500 feet of 12-foot diameter pipeline crossing a bay in Lake Mead that has water depths of up to 80 feet; and 2700 feet of 9-footdiameter steel-pipe-lined tunnel. Major site grading for a future pumping station in the area above the forebay is also included as part of the project. The project is on the schedule’s critical path for completing the first phase of a $2 billion water supply program for the Las Vegas Valley. In this paper, the owner, the designer and the construction manager present a discussion of the risk management strategies that were used to control costs, minimize project delays, and facilitate problem resolution. The discussion includes an assessment of the effectiveness of the risk management strategies in meeting these objectives. This paper will be of interest to owners and engineers planning underground projects, especially those projects that present unique risks during the construction phase.

Jan 1, 1999

By E. Yuksel

Noted as one of the 20 major economies of the world, Turkey is a semi-arid plateau between the Eurasian and the African continents. With its surface area of 780 thousand sq km, it supports a population of 70 million people. While the mining history of Turkey can be traced back as far as 7 000 B.C., mining currently generates only 2% of Turkey’s gross national product. Turkey has 77 of the 90 principal minerals that are mined world-wide. Currently, some 5 000 mine occurrences including copper, lead, zinc, iron, gold-silver, chromite, sepiolite, mercury, and coal deposits, soda ash, marble, zeolite, feldspar, magnesite deposits, as well as the world’s largest known borate deposits, have been discovered and partially explored.

Jan 1, 2004

By Shemek Oginski

The 5 km (16,194 lf) of 6.1m (20 ft) diameter TBM driven tunnel built by the J.F.Shea Co. will serve as sewage overflow storage. The TBM tunnel and four connecting tunnels excavated by drill and blast methods in hard granite will remain unlined. Based on the Geotechnical Baseline Report (GBR), the Contract documents provided a design with no required pattern of rock bolts, no probing, no pre-excavation or consolidation grouting, and lastly, no final lining of the tunnels was deemed necessary. This paper will provide a general overview of these topics with the emphasis on the actual ground conditions encountered versus the projected conditions provided in the GBR and how the GBR reflected the design of the project. Proposed modifications to the temporary and permanent ground support will be presented and the necessity of probing and pre-excavation grouting will be evaluated.

Jan 1, 2005