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By G. Tranell, L. Kolbeinsen, S. Gaal, J. Safarian

The effect of carbon material properties on the rate of MnO reduction from ferromanganese slag by solid graphite was investigated. A sessile drop technique was used to study the reduction rate of a synthetic slag containing 45 wt% MnO at 1500 and 1600 ºC. Different types of graphite substrates were used and the con-tact angle between slag droplets and substrate were measured in-situ. Moreover, the slag droplet volume during the interaction with the graphite substrates was calculated and normalised. The mathematical relationship between the slag density during the reduction and the normalised slag droplet volumes during the reduction were derived and the MnO reduction curves were then calculated. A method for measuring the slag reactivity of solid carbon was defined and used to qualify the propensity of the different graphites to react with the liquid slag. Some supplementary studies such as manganese evaporation measurement and EPMA analysis for determining the extent of MnO reduction were also carried out. It was observed that there is nota significant difference in the wetting angle of the graphite substrates by the slag, and the wetting is not changed within the temperature range of 1500-1600ºC. However, the changes in the contact angle during the slag reduction at 1600ºC are more than at 1500ºC. The kinetics of MnO reduction is dependent on the type of graphite and it is more dependent on the graphite properties at lower temperatures. On the other hand, the dominant properties of graphite on the reduction rate vary with temperature. A multivariate analysis on the graphite properties and the parameters related to the slag reactivity indicated that the kinetics of MnO reduction is mainly dependent on the temperature, and then on the graphite properties. It was also found that at1500 ºC the surface area and the CO2 reactivity are the most important graphite properties for the slag reduction, suggesting that the reactivity of carbon is rate controlling at 1500 ºC. However, the porosity related parameters are the most important graphite properties at 1600 ºC, suggesting that CO gas desorption is rate controlling at high temperatures.

Jan 1, 2007

By Tracy Brettmann

The use of rock-socketed Augered Cast-In-Place (ACIP) piles is new to the Austin and central Texas region. This case history describes the design methodology, load test results, quality control procedures and the rate of production pile installation for the first large commercial project where ACIP piles were used in Austin. The piles were 24 inches in diameter and extended through about 45 ft of alluvial materials to be socketed 6 ft into limestone. A full-scale instrumented load test was performed on a test pile that was loaded to 452 tons and held for 24 hours. Telltales were installed in the middle and the tip of the test pile. As part of the overall quality control procedures, singlehole sonic integrity logging was performed on the production piles to verify structural integrity during pile installation. During pile production, an average of 14 piles per day were installed, which is approximately seven times faster than the original design that consisted of drilled shaft foundations.

Jan 1, 1998

Resolution Copper Mine is planned to be a 2000 m deep panel cave mine with virgin rock temperatures above 80°C in rock with a high crystalline silica content. The planned run-of-mine production rate is 120 kt/day. The project is in prefeasibility evaluation. This paper discusses features of the ventilation system design, which include multiple ventilation shafts with total flow of about 3000 m³/s and both surface and underground refrigeration systems with more than 140 MW total capacity. This will be a very challenging mine to ventilate, but this work has demonstrated that it will be technically achievable with the application of existing technology.

Jan 1, 2014

By Meherwan C. Irani

The Bureau of Mines is developing a new technological approach to handling the problems of fires in abandoned coal mines and waste banks. This new technology involves the accelerated combustion of "waste" coals in place (i.e., in situ) under controlled exhaust ventilation conditions, which allows for total management of the combustion products; including utilization of the heat produced" This new concept could significantly lower the costs of reducing the environmental and public safety hazards associated with waste coal fires, and could lead to the conversion of a coal waste to a coal resource. The controlled burnout technology has progressed from the laboratory stage to a full-scale field evaluation stage at the site of an abandoned-coal-mine fire. This first report describes the site selection, evaluation, and preparation, and the design and construction of the full-scale controlled burnout installation. Subsequent reports will deal with the results of the operational field trial.

Jan 1, 1983

By Derek H. C. Wilton, David T. W. Evans

"Abstract - The Midas Pond gold prospect, central Newfoundland, is hosted by sheared and altered felsic and mafic pyroclastic rocks of the Tulks Hill volcanics, Victoria Lake Group, and has been trenched and tested by 19 diamond-drill holes. Gold values are sporadic, with the best diamond-drill intersection assaying 7.3 g/t over 0.9 m, and the highest grade channel sample containing 14.7 g/t over 1.15 m. Alteration and mineralization are confined to a 200 m wide brittle-ductile shear zone. This shear zone formed in response to regional D1 deformation, and the shear zone fabric parallels the regional S1 foliation. D2 deformation resulted in broad Z-shaped flexuring of the shear zone. The deformation was probably related to the ca. 396 Ma to 420 Ma Salinic Orogeny.Advanced argillic alteration and an extensive halo of Fe-carbonate and pyrite surround the gold mineralization. Alteration minerals include pyrophyllite, paragonite, quartz, plagioclase, chlorite, fluorite, Fe-carbonate, and pyrite. As such, the alteration seems to reflect combined epithermal (argillic) and mesothermal (carbonate) mineralizing environments. The argillic alteration and fluorite represent a regional hydrothermal effect on the felsic volcanic rocks; whereas, the Fe-carbonate and pyrite represent a mesothermal alteration associated with auriferous quartz veins. The Au, which is spatially associated with pyrite, occurs in three structurally-controlled vein sets. These veins are confined to the contact between a highly deformed breccia (the banded mafic tuff) and structurally overlying, altered felsic tuffaceous rocks. The vein sets include: V1 boudinage veins that parallel the shear-zone fabric (C-shear veins), and V2 and V3 extensional fracture veins which are controlled by an S2 fracture cleavage. V1 veins are the earliest and contain the lowest concentrations of Au. V2 and V3 veins are concentrated within the hinges of the D2 flexures.Pb isotope data for galena separates indicate that the Pb in the vein systems was probably of local derivation. Sulfur, C, and O isotope data for mineral separates are similar to data for typical mesothermal lode gold deposits. Fluid inclusion data suggest the presence of at least three hydrothermal fluid types in the region, viz., (1) an early saline fluid which produced the argillic alteration, (2) a CO2-bearing fluid directly related to the auriferous mineralization, and (3) H2O-NaCl fluids which flowed through the Midas Pond shear zone at a lateral distance from the zone of mineralization. The mineralizing fluids are interpreted to have been CO3 -2-rich types which originated through metamorphic dehydration and decarbonation of mixed island-arc and continental crustal rocks. Gold precipitation resulted from the reaction of these fluids with the Fe-rich breccia unit. Pre-existing and simultaneously crystallizing pyrite served as loci for Au precipitation."

Jan 1, 2000

By Timothy D. Stark

Jet grouting has increasingly become a ground improvement technology used to address seepage concerns and provide strength improvement to soils underlying dams. The technique of jet grouting uses high pressure/volume jet fluids to erode existing soil, evacuate some or most of the soil, and mix the remaining cuttings with cement slurry to form soilcrete. While considered a useful technology, this paper discusses some of the problems that can develop while jet grouting in or below a dam with an operational reservoir and seepage condition. Jet grouting experience at Tuttle Creek Dam indicates concerns with respect to ground fracture; spoil return, column diameter consistency, and homogeneity of resulting soilcrete. Recommendations are presented to increase monitoring of downhole parameters during jet grouting to better understand the downhole pressures and soil response during jet grouting.

Jan 1, 2012

By J. L. Konchesky

In gasifying pulverized coal with steam and oxygen, the particle size of the coal fed to a gasifier should be as small as economically possible. A potential way to achieve this advantage is to reduce the particle size of the coal by passing the coal-steam mixture at high velocity through a heated tube coil before the mixture enters the gasifier. To evaluate this method the Federal Bureau of Mines flashed coal-water slurries in externally heated metallic tube coils to determine the extent of size reduction. The first of two different laboratory-scale apparatus reduced the average particle diameter of subbituminous C coal from 190 to 110 microns at an outlet velocity of 330 feet per second (f.p.s.). At the same outlet velocity, a second apparatus reduced the average particle diameter from 250 to 140 microns. An increase in velocity produced more finely divided coal, but variation in temperature and pressure had no effect except as they affected velocity. Virtually the same size reduction was noted for five ranks of coal at equal velocities. The rate of increase in particle-size reduction with increase in velocity decreased with a decrease in particle size. The pulverizing mechanism was concluded to be abrasion of the particles with each other and with the tube wall.

Jan 1, 1961

By Nolan Eckroade, Nigel Pereira

Wireless electronic blasting systems are a new technology that enable truly wireless initiation through rock, air and water. This is achieved using low frequency magnetic induction waves to wirelessly send a firing command to groups of in-hole primers. Fully wireless initiation not only removes the limitations imposed by a wired connection to each primer in a blast, but also enables users to alter the paradigm of conventional mining techniques to advance operational productivity and reduce personnel exposure to high-risk activities. While initially deployed in underground applications, wireless electronic blasting is now being used in the open cut environment. To capture the early impacts in surface mining operations, case studies conducted at three surface mines evaluated blasts utilizing a wireless electronic blasting system against baseline blasts using conventional, wired initiation systems. The purpose of this paper is to outline the specific learnings associated with wireless electronic blasting in surface mining to date. The paper will include references to these specific case studies as well as benefits realized and applications for the future.

Relatively few longwall mines in the U.S. operate under multiple seam conditions where the two seams are less than 200 ft apart. This paper describes the experience of six that do. These operations are located in PA, WV and UT, and include examples of both undermining and overmining. Some operate above or beneath their own workings, others are in historic mining districts and must contend with abandoned mines that are decades old. The lessons that these mines have learned cover a broad range of topics, including: • Whether to stack gateroads or place them under old gob areas; • How to size pillars and select artificial support to cross longwall stop lines; • How to use yield pillars to minimize multiple seam stresses and coal bump potential, and; • When to anticipate the creation of pathways for gas, water, or oxygen between current and abandoned gobs.

Compagnie Miniere Esperance (CME), a mining company based in French Guyana, operates a gold primary ore body in open pit. The ore is processed through crushing, grinding and gravity separation. Tailings are stored in a ?fine? pond. Analyses of the fine ponds proved a residual gold grade sufficient for a chemical treatment. However, direct cyanidation would require a too large installation, regarding the local conditions (accessibility, supplying and rainforest meteorological conditions). It has been then decided to test the feasibility of a pre-concentration using flotation. Lab tests have been carried out by SGS Lakefield (Canada) in March 2007, which proves the technical feasibility. Therefore, CME asked Caspeo to: ? Carry out an on-site flotation pilot campaign. ? Design an industrial flotation circuit. The tailings reprocessing will contribute to a better tailings management and a dry up of the gold resource, limiting the risk of illegal mining after remediation of the CME site. CME MINE The Esperance gold mine is located in French Guyana, in the vicinity of several gold deposits as Omaï, Rosebel or Camp Caïman, holded by Iamgold and Newmont. These main gold deposits are located on the figure 1. Esperance was put into operation in the early 90?s. The first years were devoted to the mining of alluvial gold in the gravel of the Esperance Creek. Since then, operation was led in the primary gold deposit. Annual production is on average 254kg for a total production in fifteen years of 4300kg. Geology Esperance deposit is located in the greenstone belt of the Guyana Shield. Mineralization is in tectonic contact between sedimentary basin of Maroni and a granitic massif. Clastic series, composed of conglomerate and lamina sandstone, overlie a volcano-sedimentary basement (series called "Paramaca"). The area is strongly folded by shear movements, resulting from granite deposit. Gold is in interlacing quartz veins intersecting the clastic series. Gold is present in association with pyrite. Other elements, as silver or arsenic, are in negligible quantity. Exploitation The Maroni River is the only access to the Esperance mine. Only the saprolite and a part of the transition rock are extracted in the open pit. Excavation works are done using shovels Hyundai 450 (4 units) and haulage works using articulated dumpers Terex TA35 (4 units). These two sorts of equipments are presented figure 2. Mill The mill is composed of crushing and grinding processing plants. After gravity concentration, both plants produce tailings that are stored in two ponds: the first pond contains coarse product which segregates the particles crushed to 2mm upstream and settled clays downstream; the second pond contains the fine product made of particles ground to 200µm. These two ponds, bordered by dams and diversion canals, are located on former alluvial sites of Esperance Creek (see figure 3). [ ] The CME mill is currently producing gold concentrate, with a global recovery of about 67%. The ore is crushed by one jaw crusher and two hammer crushers. The ore then passes through a Knelson KC 48 gravity concentrator, producing a first gold concentrate. The

Jan 1, 2009

By Douglas W. Christie

Deep foundations in Washington, DC have played a role in the city?s development since the 19th century. Designers of government and commercial buildings sought deep foundations initially to minimize settlement of structures. As the western portion of the National Mall was made by filling in portions of the Potomac River, numerous memorials and monuments on the Mall required deep foundations. In recent years deep foundations have been used to allow underground construction for various reasons. Commercial developers have sought to maximize the use of sites by developing below-grade space for parking to meet code requirements and offset the limits on building heights. Underground museum and gallery space has been constructed to expand public space while preserving open space above grade. Access and security concerns have prompted the design of underground visitor centers rather than above-grade structures.

Jan 1, 2006

By Ronald P. Hollenbeck

Shales in the Appalachian Region of Kentucky and Tennessee were sampled and tested to determine their use as raw materials for the manufacture of lightweight aggregate by the rotary-kiln method. Nine samples were obtained from eastern Kentucky and 143 samples were obtained from eastern Tennessee. As a result of preliminary testing of these samples, two sources in eastern Kentucky and 11 sources in eastern Tennessee were resampled for rotary-kiln tests. The rotary-kiln tests showed the two sources in Kentucky and seven sources in Tennessee contained shale that would produce satisfactory aggregate. Lightweight aggregate processed from these nine sources was tested in concrete shapes and was found to be suitable for use in structural concrete.

Jan 1, 1968

By K. Galovich, P. Krivokuca

"Quinsam coal mine is located about 25 km west of Campbell River on the east coast of Vancouver Island, British Columbia. Using continuous miners in a fully mechanized retreat room-and-pillar operation, it produces low sulphur, “super compliance” thermal coal for domestic and international markets at a rate of about 2600 t/d. Currently, 65 people work at the site, including some corporate employees.Opened in 1993, the Quinsam mine had a dismal safety record until 1997. Lost time injuries and medical aids were unacceptably high. In 1998, a change in corporate structure brought a change in safety attitudes; a total and unequivocal commitment to safety as job No.1 by corporate and site management. This commitment was clearly spelled out in a new mission statement, circulated to all employees by the new President and CEO, David Slater: “Safety is job No. 1; Production flows from safety; and Think safety at all times.” As well as re-defining workplace safety practices, QCC tightened engineering controls and enforced strict adherence to mine plans.This paper provides a general background to the mining operation, and describes the safety practices that have resulted in an enviable safety record in recent years, reflected by provincial and national recognition."

Jan 1, 2004

Paper presented at the IAGOD international symposium on mineralization related to mafic and ultramafic rocks held in Orleans, France, 1-3 September 1993. Phases of the Ir sub-group are present either as inclusions in or interstitially to chromite and are unaffected by (or only altered in situ during) hydrothermal processes. By contrast, almost all phases of the Pd sub-group are located in a secondary textural setting - in fractures in chromite or between fragments of brecciated chromite. The different settings indicate that the mineralisation episodes were associated with magmatic and hydrothermal stages respectively. The presence of an included Pd-group mineral in a hydrothermally Pd-group mineralised chromitite sample suggests that the hydrothermal Pd-group minerals were at least partly derived by remobilisation from magmatic deposits in the chromitite pod. These observations indicate that Pd-group elements are more mobile than Ir-group elements under hydrothermal conditions and point to the potential for hydrothermal platinum and palladium mineralisation in favourable environments

Apr 1, 1994

By Fidelis T. Suorineni

Rapid drifting enables quicker access to orebodies, higher production rates and a resultant reduction in production cost. The Mining Innovation, Rehabilitation and Applied Research Corporation (MIRARCO) funded by the Canadian Mining Industry Research Organization (CAMIRO) has developed a methodology for safe rapid drift development within the underground metalliferrous mining industry in Canada According to industry survey, about 36% of drift development cycle time is spent on support installation. MIRARCO has developed a methodology for safe rapid drift development based on minimizing time spent on support installation. The methodology includes a critical review of the rockmass classification systems, examination of current support practices in the mining industry and civil tunneling, review of rapid drift development practice in South Africa, introduction of risk hazard procedures to account for material property variability and the development of a WIZARD as a quick decision-making tool for the implementation of the procedures. A comprehensive field data collection procedure was put in place and data collected from various mines to verify and calibrate the support selection rationale. The findings of the research programme resulted in the development of an improved rockmass classification system and showed that construction effects have drastic influence on support levels but is often not accounted for in assessing support levels. Stress effects and structurally controlled failures are the other important factors to take into account in rapid drift development. Three support classes were established for safe rapid drift development as No Systematic Support, Light Support and Strong Support. The support levels took into account cost, rate of installation and safety based on compatibility with ground characteristics. This paper describes the methodology for safe rapid drifting within the underground metalliferrous mining industry in Canada and highlights the key issues and major drivers behind their continued development at the Geomechanics Research Centre within MIRARCO.

May 1, 2004

By Mohammad Djavid

The one-pass tunneling pipe jacking method has often been the most schedule and cost efficient method for the pipe line installation. The main challenges in jacking pipes larger than 108 inches and for longer runs are: transportation and logistics, requiring high jacking forces, keeping line and grades, control of ground surface settlement, providing adequate external lubrication, and the potential of damaging the joints and pipe spigots. In recent years, 144" diameter pipes have been jacked for short runs of up to only 300 feet. In this article design and construction of installation of up to 1,000 linear feet run of 144-inch internal diameter, reinforced concrete pipes without intermediate jacking station in Chicago O?Hare International Airport are discussed. The article also presents discussions regarding the subsurface saturated silt formation, shallow cover, dewatering, jacking and receiving shafts, jacking forces, lubrication and settlement data.

Jan 1, 2008

By I. A. Mwamba

Plain and alloyed titanium aluminides of composition Ti-47.5 at.% Al were prepared by melting commercial-purity titanium and aluminium with additions of 1 at.% precious metal. The as-cast alloys were subjected to potentiodynamic scans in 5, 15, and 25 wt% HCl aqueous solutions at room temperature and compared for their abilities to spontaneously passivate. Addition of precious metals resulted in a general improvement of corrosion resistance by increasing the open circuit potential to more noble values. Addition of 1 at.% gold or silver to titanium aluminide did not significantly increase the corrosion potential (Ecorr) above that of the plain titanium aluminide alloy, indicating that gold and silver are not sufficient cathodic modifiers to improve the corrosion resistance of titanium aluminide in all the solutions tested. However, platinum, palladium, and iridium additions shifted the corrosion potentials to the position of the passive region of plain TiAl for all solution concentrations. This indicated that TiAl alloyed with these platinum group metals would passivate spontaneously by cathodic modification. TiAl alloyed with palladium performed the best in 5 wt% HCl solution with the most positive corrosion potential. In 15 wt% HCl solution, alloys with platinum exhibited the most positive corrosion potentials, while alloying with iridium or palladium revealed more negative corrosion potentials. Thus, palladium alloying led to the best cathodic modification of titanium aluminide in low-concentration HCl solution, whereas platinum and iridium alloying additions resulted in the best cathodic modification of titanium aluminide in high-concentration HCl solutions.

Jan 1, 2013

By Chuck Edwards

"Milling operations in northern Saskatchewan’s Athabasca Basin have produced uranium continuously since 1975. Over that period, the Athabasca Basin has been one of the world’s premier uranium camps, yielding more than 660 million lb of U3O8. In this paper, the author describes former and current milling operations and discusses why and how the milling process has changed and developed over the past 35 years. The author’s considerations for the future of uranium extraction in the Athabasca Basin close out the paper.INTRODUCTIONThe roughly oval Athabasca Basin in northern Saskatchewan occupies nearly one third of the surface area of the Saskatchewan Shield. Its sandstone-like deposits lie unconformably on the older basement. The basin hosts many high-grade unconformity-type uranium deposits(Saskatchewan Energy and Resources, 2010) for which the Athabasca Basin is world famous. Uranium production in the Athabasca Basin has come from four mills. In the order of startup these are Rabbit Lake, Cluff Lake, Key Lake and McClean Lake. General data (AREVA, 2010; Cameco, 2010; Denison 2010) for each mill are shown in Table 1."

Jan 1, 2011

The morphological changes that gold undergoes during transport in gravel-bed rivers are a function of transport distance in particular, as well as bedload material, river gradient and velocity, and bed roughness. Gold size, shape and outline are modified by abrasion, flattening, folding and breakage during transport. The resultant morphological characteristics can be used to predict source types, source location and transport distance, as well as the origin and dispersal patterns of gold in ancient placers where the transport history is unknown.

Jan 1, 1998

Implementation of Fine-Screening in Preparation of KGHM PM SA Sandstone-Carbonate Copper Ore for Flotation

Sep 13, 2010