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By Kouichi Tomisawa

Two bridges were constructed for extension work of Central Hokkaido Connection Road in 2005 at two different sites. Pile group foundations were employed for the foundations of abutments of the two bridges. In order to assess the performance of the constructed piles in the sites and to obtain design parameters for design in future, static alternating cyclic horizontal load test was carried out on one of the open-ended steel pipe piles constructed at each site. The ground at one site was characterised as a thick deposit of volcanic soils, and the ground at the other site was characterised as a very soft peat layer near the surface. In this paper the results of static alternating cyclic horizontal load tests on the piles at the two sites are presented and discussed in detail.

Jan 1, 2006

By Debasis Deb

The first version of the longwall strata control and maintenance system (LSCMS) has been successfully developed by the Strata Control Re¬search Team at the University of Alabama. The system includes a software package designed to monitor shield leg pressure, interpret the data and predict the forthcoming roof loads and the existence of geological anomalies. It can also detect maintenance problems of the face equipment. The LSCMS was installed underground and connected to the surface terminals at Drummond's Shoal Creek Mine in Alabama. The system has proven to be a useful and practical system for improving safety and efficiency in coal-mining operation. The Shoal Creek Mine is a new, large coal mine operated by Drummond with two longwall panels. The Blue Creek seam is the primary source of coal production. It is located at a depth of 275 to 440 m (900 to 1,450 ft) below the surface with an approximate 2% southwest dip. Typical strata conditions are represented by two stratigraphic columns (Figs. la and b). A fireclay/dark shale parting (called Middleman) 0.2- 0.7-m- (1- to 2.5-ft-) thick exists between the Mary Lee and Blue Creek seams. Mining conditions vary from area to area. This mainly depends on the Blue Creek seam thickness that ranges from 0.9 to 2.9 m (3 to 9.5 ft). The thickness of the Mary Lee and the parting is relatively consistent with a to¬tal of 0.9 m (3 ft). They are mined when the Blue Creek seam becomes thinner. In most of the panels, the immediate roof is composed of sandy shale 1.5-

Jan 1, 1997

By S. E. Phillipson

Underground mine mapping is a critical component of understanding the controls on ground instability. Many relatively localized examples of ground failure are associated with geologic features, such as faults, joints, compaction zones, or sedimentological transition zones. In contrast, long-running, directional roof falls are associated with regionally directed horizontal stress fields, which are induced by tectonic plate interactions in the earth?s crust. When stress-related features are distinguished from geological features, underground mapping can be an effective method for inferring the direction of horizontal stress at individual mines. Comparisons with data compiled in the World Stress Map confirm that underground mapping can be a valid method for determining the orientation of maximum principal horizontal stress at a variety of scales, ranging from individual mines to an entire mining district or coal basin. Comparisons are presented between the maximum horizontal stress directions inferred by MSHA?s Roof Control Division through underground mapping and the azimuths of maximum horizontal stress in the World Stress Map database for North America?s Pennsylvanian-aged Appalachian, Illinois, Black Warrior, and Arkoma Basin coal fields. The comparison indicates that azimuths are similar for both data sets, even where variations in the direction of horizontal stress are present. It is interpreted that inconsistencies in direction are attributable to near-surface affects such as deeply incised stream valleys, or to fault zones that represent heterogeneities in the crust.

Jan 1, 2009

By Sikko Doornbos

For the extension of the Paper Mill of Parenco in Renkum, the Netherlands, the application of a pile foundation was required. The demands for this pile foundation were very explicit a vibration free and soil displacing pile systems with low allowable settlement. Another important aspect was the total amount of piles (originally over 1600 auger piles) which had to be executed within 3 months, in very difficult and unhomogeneous soil. Based upon these conditions the Tubex Grout Injection Pile was chosen to be used for this project. This system involves the drilling of a steel tube with a conical pile shoe while grout is injected at the point simultaneously, creating a mixed-in-place layer around the tube. INTRODUCTION After extensive marketing, the board of directors of Parenco, decided to a large extension of the production capacity of its paper mill by building a new production building called Paper Mill 1 or PM-1. The new PM-1 extension had to be constructed beside the existing PM-2 because of limited terrain. The site is located right between the Rhine river and Renkum, approximately 15 kilometers (10 miles) west from Arnhem (see figure 1). The construction involved the building of the PM-1 extension of approximately 250 meters (820 ft.) long by 40-60 metres wide (130-200 ft.). The main structure was to be constructed of precast concrete beams and columns.

Jan 1, 1987

By D Jensen, L Riffo, S Yu, F Traczyk, D Meadows

With the steady increase of molybdenum demand worldwide and the favorable molybdenum market, many technological innovations on both process and equipment have been developed and applied in many modern molybdenum plants around the world. This paper introduces the most commonly used molybdenum flotation flowsheet, together with the introduction of the flotation chemistry. Many different types of flotation cells are used in modern moly plants, and each type of flotation cell has its own unique advantages suited for particular ore and process conditions. This paper tries to provide some insight and guidelines in flowsheet development and flotation cell selection in the molybdenum plants.CITATION:Meadows, D, Jensen, D, Traczyk, F, Yu, S and Riffo, L, 2013. Molybdenum flotation circuit and flotation cells, in Proceedings MetPlant 2013 , pp 387-398 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013

By John Addison

Experimental animal studies comparing asbestos and non-asbestos varieties of tremolite indicate tremolite asbestos is markedly more carcinogenic. By direct analogy, the differences in carcinogenicity between tremolite asbestos and non-asbestos prismatic tremolite should be the same for the other types of amphibole that also crystallize in the asbestos and non-asbestos habits. The earliest of the experiment animal studies, done more than 25 years ago, have design limitations by modern standards including the use of injection or surgical implantation as the route of administration rather than the more relevant route of inhalation. However, the differences in the carcinogenicity of amphibole asbestos and non-asbestos amphiboles are sufficiently large to be clearly discernable even with the study limitations. Together with later studies on these and related minerals, there is strong evidence of a much lower hazard associated with the shorter, thicker fibers of the non-asbestos amphiboles, than is found for the asbestos analogues of the same mineral. It is possible that the non-asbestos amphiboles are no more hazardous than other silicate minerals widely considered nuisance dusts. © 2007 Elsevier Inc. All rights reserved. Keywords: Amphibole; Asbestos; Tremolite; Carcinogenic

Jan 1, 2007

By Jacob Carr, Chenming Zhou, Nicholas Damiano, James Noll, Jingcheng Li

Machine-related injuries are one of the major safety concerns in underground coal mines. Severe injuries and fatalities occur when a miner is struck, crushed, or pinned by mining equipment such as a continuous mining machine (CMM), shuttle car, or a scoop. Proximity detection systems (PDSs) have been applied in mining to reduce these types of injuries and fatalities. All of the PDSs that are currently approved by the Mine Safety and Health Administration (MSHA) for use in underground coal mines are magnetic-field based and could be affected by metallic objects such as trailing cables. Researchers from the National Institute for Occupational Safety and Health (NIOSH) investigated the influence of trailing cables on the performance of PDSs. In particular, the magnetic field coupled from proximity system generators to a de-energized trailing cable was characterized. The results show that significant energy can be coupled from the proximity system generators to a trailing cable when there is a closed loop in the cable. The effect on PDS performance from the magnetic field radiated around an energized trailing cable was also quantified for different current amplitudes in the cable. It is shown that the magnetic field caused by the electric current in the trailing cable mainly consists of a 60-Hz signal and its harmonics which causes little interference to the PDS. The results presented in this paper can help PDS manufacturers to design better systems that are more immune to these effects.

By T. A. Muhlare

The use of electrolyte additives to smoothen cathode deposits during copper deposition is practised worldwide. These additives absorb on the cathode surface and take part in the electrochemical crystallization process. However, these additives also affect the quality of the cathodes when they are inadequately controlled. Electrolyte additives used by Palabora are glue, thiourea, Avitone and chloride. Their effects were determined on cathode quality, the size of the current density region that gives the desired compact morphology, and current efficiency. This was done in a small-scale cell. Small cells have different hydrodynamics from industrial-scale cells, which makes it difficult to simulate the operation of industrial cells in a laboratory. The approach used here was to use a rotating cylinder cathode to attain controlled hydrodynamics. The rotation speed was chosen to give a diffusion layer thickness that is similar to that of an industrial-scale cell. It was shown that even fairly small changes in the additive levels can significantly affect the cathode morphology, and the current density range over which this morphology can be obtained. Keywords Copper, electrorefining, glue, thiourea, avitone and chloride.

Jan 1, 2011

By Ronald J. Mathis

The objective of this contract is to design, build, surface test, and evaluate a breadboard prototype of the Variable Wall Mining System so that data are available for the design of a production machine. The Variable Wall Mining System (VWMS) consists of a series of side cutting augers, connected end to end, and distributed across a panel. Supplying rotary power at the end of the string and anchorage from conventional longwall roof supports, the augers are sequentially thrust into the face and then lifted to the roof to extract the coal in a continuous manner. The augers not only cut but also transport the coal. The effort described in this report summarizes the operation characteristics of the VWMS, the design methodology used to develop various working models, the surface testing of a ½ -scale version of the VWMS, prediction of power requirements and performance potential of a full-scale system, and a critique of the VWMS concept, conclusions, and recommendations.

Jan 1, 1987

By E Breese

The Grey River dredge is the first large scale alluvial operation to be permitted under the Mining Act 1971 and the Water and Soil Conservation Act 1967. The experience of Grey River Gold MiningLimited in pursuing these statutory approvals has identified weaknesses and strengths in the present system and problems which need to be resolved. The Company has learnt lessons, which if heeded, will assist future large scale alluvial mining projects.

Jan 1, 1989

A President, soon after he is appointed, sees looming ahead of him the Presidential Address; and in something approaching despair wonders what he can possibly talk about which might hold the interest of his audience. After various casts about, it occurred to me that perhaps prospecting, and more particularly prospecting in Australia, might provide a subject. This is because, 'in the first place, 'prospecting is passing from the stage of chance surface discovery to that of systematic search applying scientific methods to theproblems involved, and in the second, it is the section of the industry with which I have been concerned through much of my: working life. As it makes an address of this sort more interesting if it includes specific reference to actual experience, I hope you will bear with me in such references to actual prospecting as I may use to illustrate the argument. Prospecting has always carried the glamour of sudden wealth. The picture of the prospector engaged, perhaps for years, in fruitless search suddenly coming on riches beyondhis hopes is, deeply etched in the Australian imagination. In few other places has the fervour of prospecting run higher than it did in Victoria in the generation beginning little more than a century ago following the discovery of gold.People arrived from overseas in great numbers. Most of them proceeded to: the goldfields. They moved in thousands from new find to new find. In 'so doing' they determined much of the course of the State's development. The experience of prospectors led them to formulate all sorts of theories little impeded by awkward facts, to account for the apparently unpredictable occurrence of gold.The ideas which men followed, occasionally to success, and which they were prepared to back with all they had were strange and, various, many stories are told of them.

Jan 1, 1959

By Gregory M. Molinda

Historically, miners have known that roof rocks originally composed largely of mud were prone to slaking and deterioration when exposed to water and humidity. Mine Safety and Health Administration (MSHA) records show that roof falls are more prevalent in summer and late fall. Field data shows higher bolt loads and increased room convergence in summer months. Laboratory data shows that very high internal pressures can be generated by significant strain in clay-rich rocks. In summer months humidities ranging from 70-100% can cause rock strains up to 7%, and rock pressures of 14,000 psi, more than enough to break apart weak shales and fireclays. The National Institute for Occupational Safety and Health (NIOSH) conducted wet/dry immersion cycling of clay-rich rocks. Results show that the rocks most prone to moisture deterioration are fireclays, claystones, and sandy shales, all of which have disrupted bedding. Of the 7 mudrocks with a weatherability index above 40%, none showed consistent fissile bedding. Black shales were surprisingly resistant to wet/dry water immersion cycling. Generally, mixed rocks (stackrock), typically susceptible to horizontal stress, are more resistant to moisture-deterioration. Mine roof rocks tested with moisture sensitivity ratings above 50% (moisture sensitivity index ranges from 0-100 with 100 being the most sensitive) all came from mines which had roof skin problems and used supplemental support to prevent rock fall injuries. Some roof rocks showed lateral variability of moisture sensitivity values, suggesting the need for more samples in highly varying roof rocks. Swelling strains of mudrocks showed that almost all of the swelling occurred in the first 24 hours after immersion. The wet/dry immersion cycling test used provides an accurate, quick and inexpensive method for estimating the moisture sensitivity of mudrocks. With this information mine operators can begin to anticipate hazardous ground and prepare appropriate roof support.

Jan 1, 2006

By D Craw, D Wilson, D Chappell

Gold is extracted by cyanidation of a sulphide-rich concentrate at Macraes mine, and after cyanidation, the concentrate is discharged to tailings impoundments. The concentrate tailings were discharged to a dedicated concentrate impoundment from 1989 to 1993, afterwhich they were blended with the flotation tailings. Since mid-1998, concentrate tailings have been redirected to the dedicated concentrate impoundment. The concentrate tailings contain up to 1 ppm gold, and will be reprocessed in the future. However, it is a regulatory requirement that a contingency plan be in place to rehabilitate the concentrate tailings should the mine operation cease for any reason. Initial predictions suggested that the sulphide-rich tailings would oxidise and acidify, creating a potential long term environmental problem. Investigations of the state of the tailings after 4 years show that these predictions were overly conservative. Only minor oxidation has occurred in the upper 2 metres of the tailings where the pH has locally dropped from 10 (discharge condition) to between 7 and 8. Below 2 metres, the tailings are essentially unchanged from their deposition state. The low rate of change in the tailings is due to their very low permeability which in turn is a consequence of the fine grain size (ca. 15 ¦m). Dewatering is extremely slow, and incursion of oxygenated water is negligible. Calculations suggest that water movement over 30 m will take at least 100 years and possibly 1000 years. The contingency plan is to capitalise on the very low permeability and keep the tailings from drying with a semipermeable cap. A layer of limestone will be added to the top of the tailings, beneath the cap, to enhance alkalinity of any percolating water. If acidification does occur, contrary to expectations, any acid produced will be neutralised by underlying calcite-bearing schist, schist in the concentrate impoundment wall, and the flotation tailings immediately downstream. In addition, dilution by alkaline ground and surface waters would further ameliorate any acidic discharge.

Jan 1, 1998

By Mina M. Shinouda

Brightwater West (BT4) represents the state of the art in utility tunneling, namely a long relatively small diameter, soft ground tunnel, with no intermediate shafts, under significant groundwater pressures, requiring very precise survey control in order to hit a small exit window. The tunnel is over 6.4 km (4 miles) in length, is expected to encounter active earth pressures of over 5 bars in glacial geology, and a planned hole through into a shaft eye constructed at 45.7 meter (150 feet) below the water table. Despite the fact that all of these challenges have been previously overcome in larger diameter tunnels, the technical solutions are much more challenging in a smaller diameter due to the lack of space available for implementing the equipment and techniques required. In addition to the technical challenges, the project is faced with many of the constraints designed to minimize the impact of these types of projects on the neighboring community and environment. The work shaft for BT4 is within 15.2 m (50 feet) of Puget Sound and is on a site that was previously occupied by petroleum storage tanks, and all of the tunnel muck has to be removed from the site by barge as trucking is not allowed by contract. The paper addresses the work performed during the preparation for tunneling stage of this project both in assembling the TBM and in preparing the site for its arrival.

By Raymond Rivera

El presente texto describe la evaluación desarrollada por INGEMMET donde se analiza el potencial de los depósitos minerales en el Batolito Andahuaylas, Yauri, así como el potencial de algunas zonas que presenten características geoeconómicas importantes, utilizando herramientas geológicas como geocronología, isótopos radiogénicos, geoquímica de rocas y sedimentos, petromineralogía y geología estructural.

Sep 12, 2011

By Bill M. Stewart

Since 1974, a large amount of data has been developed concerning the physical properties and stability characteristics of waste generated by the mining and preparation of bituminous coal. However, very little information has been developed on the properties and characteristics of anthracite waste. During this Bureau of Mines research project, coarse anthracite breaker refuse from five sites in eastern Pennsylvania was sampled and the physical properties, which indicate stability characteristics, were determined in the laboratory. Coarse anthracite breaker refuse is quite similar to coarse bituminous refuse in chemical and mineralogical composition. However, the physical properties of the anthracite waste materials tested are different from those of coarse bituminous refuse. For the coarse anthracite breaker refuse tested, the average maximum laboratory density is 113.2 lb/ft3, the average angle of internal friction (direct shear) and average cohesion are 30.2° and 2.6 psi, respectively, and the average permeability (four sites) is 1.24 x 10-2 cm/sec. Stability analyses were conducted on six theoretical anthracite waste embankments. These analyses show the effects on minimum safety factors of geometry, phreatic surface level, and physical properties.

Jan 1, 1983

By G. R. Dunning, M. R. Wilson

"Abstract - The early Paleozoic accretionary tectonic regime that was established along the Laurentian margin of the Newfoundland Appalachians provided a favorable setting for shear-hosted gold mineralization along a major terrane suture, the Baie Verte-Brompton Line. The Stog’er Tight prospect is one of several mesothermal-style gold occurrences hosted by shear zones within accreted ophiolites and oceanic arc terranes on the Baie Verte Peninsula. It is an epigenetic, stratabound deposit that is confined to shallow-level gabbro sills within the volcanic cover sequence of the allochthonous Point Rousse ophiolite complex. Gold mineralization at Stog’er Tight is associated with hydrothermal mineral assemblages represented by chlorite-calcite, sericite-ankerite, red albitepyrite (±Au) and chlorite-magnetite alteration zones. Gold occurs with pyrite within the intensely altered gabbro, along the margins of syn- to late-shear, quartz-rich, replacement veins.The Stog’er Tight gabbro served as a rigid body conducive to shear deformation and fluid penetration, whereas, its high Fe-Ti oxide content induced fluid oxidation and gold-pyrite precipitation. Hydrothermal alteration involved progressive CO2, S, Na, and LILE metasomatism, along with significant enrichments in the REE, HFSE, and Th in the high-grade ore zone. Temperatures of vein formation and alteration are constrained by oxygen isotope thermometry to be between 250°C and 480°C. Isotopic compositions of vein quartz from the Stog’er Tight prospect are uniform (??O = +12.5 ± 1‰) and fall within the range cited for many shear-hosted, auriferous quartz veins.A U-Pb zircon igneous age of 483 +3/-2 Ma for the Stog’er Tight gabbro is consistent with its stratigraphic correlation with other Ordovician ophiolitic and volcanic arc/back-arc assemblages in Newfoundland. The U-Pb age of a rare variety of hydrothermal zircon recovered from the high-grade ore zone directly constrains the timing of gold mineralization to 420 ±5 Ma, in accord with a major orogenic episode of Silurian age that produced many of the magmatic and metamorphic rock suites in north-central Newfoundland. Our results are consistent with a post-peak metamorphic, late-magmatic model for gold mineralization that occurred during the waning stages of Silurian orogenesis, driven by emplacement of I-type granitoid intrusions into the crust."

Jan 1, 2000

Standards And Laboratory Monitoring In Gold Assay Key Components Of Best Practice

Jan 1, 2005

By Fermont F. Clarke, Others, Paul Zinner

"INTRODUCTION The Edison mine comprises workings on two irregular spodumene-bearing pegmatite dikes which outcrop near the town of Keystone in the southern portion of the Black Hills of South Dakota. The Bureau of Mines conducted an investigation of the Edison mine as part of a comprehensive study of the lithium mineral-production possibilities in the Black Hills area. The work was undertaken during the Second World War, when the demand for certain lithium salts and compounds exceeded the then small productive capacity of the industry.During the course of the project, the Bureau of Mines completed 13 diamond core-drill holes, aggregating 2,114.5 feet of drilling. Twenty-six cannel samples were taken from the main Edison shaft, and 13 miscellaneous samples were obtained to permit analysis of the efficiency of phases of mining and sorting operations. Metallurgical tests were made by the Bureau of Mines to investigate the feasibility of beneficiating spodumere-bearing ores from the Edison mine. 3/"

Apr 1, 1948

By Halvorsen N

For mining medium-hard materials on the surface, "Continuous Surface Miners" have been employed for some years. The latest generation surface miner extends the performance of this type of machine to the point where the same cost efficiencies can now be achieved in medium-hard materials as has been achieved in softer materials by machines such as the bucket wheel excavator. The paper explains briefly the technology of the Krupp Surface Miner (recently released to the market) and develops the costs of ownership and typical operating costs. Comparisons are made between a shoveLtruck system and Krupp Surface Miner (KSM) systems based on both truck and conveyor transport systems. Further benefits of mining with the KSM, such as environmental, selective mining and improved product reovery are discussed briefly. The equipment is now available to mine semi-hard materials (with compressive strengths up to 60MPa) on a continuous basis and reap the benefits which continuous systems can deliver. All new and existing open cut mines should review their costs with regard to this technology.

Jan 1, 1990