Search Documents

By John C. Edwards

A computer program, developed for the Bureau of Mines under contract, predicts in a quasi-steady-state approximation the ventilation and contaminant concentrations and temperatures when a fire occurs in a multi-level mine. For periods of time in which there is no significant change in the ventilation, yet a fire is producing fumes, a real-time fume concentration throughout the mine is calculated. Multiple and time-variable contaminant sources can be simulated. Recirculation paths that can develop provide a mechanism for increasing the fume concentration in the mine network and are identified by the computer program. This report contains a listing of the Fortran computer program as well as the required format of the input data. Two examples are provided of the real-time spread of smoke from a fuel-rich fire throughout a multilevel mine. The first example considers an operational exhaust fan as well as a booster fan. The second example evaluates the real-time smoke spread following a failure in the exhaust fan; recirculation occurs in this latter case.

Jan 1, 1982

By James P. Stewart

This case history describes the engineering design and construction for the Contractor of a 35-ft-deep excavation for an 800-square-foot addition to an existing sewage pump station. The site posed unexpected geotechnical complications that included deep gravelly soil, a history of local construction difficulties, groundwater consisting of heavy salt brine, and the need to underpin the existing pump station. The project took an interesting twist when the Owner issued a change order limiting the dewatering discharge to a fraction of that required to lower the water table. This documents the interesting circumstances of this job and documents the unusual subsurface conditions in the Syracuse, NY Lakefront area.

Jan 1, 2003

By E. C. Westman

Anomalous geologic or stress-induced conditions can create a hazardous working environment for underground miners. Seismic attenuation tomography provides a valuable tool for understanding static and dynamic conditions induced by mining. As a longwall shearer cuts coal, it generates seismic energy. As this energy travels through the rock mass it is attenuated in a manner proportional to the degree of fracturing of the rock mass. By calculating this attenuation at specific locations underground, the degree of fracturing of the rock mass, and hence the relative stress state or material properties can be inferred. The goal of this work has been to create a tool which can be easily used by the mining industry to obtain information about the distribution of stress concentrations or material properties across a broad area in advance of mining.

Jan 1, 1996

By Flor De Cock

The paper reflects part of the work from the European Regional Technical Committee on Piles (ERTC3) during its mandate between 1994 and 1999, and, in particular, describes the find­ings from an International Seminar held in 1997 in Brussels on European practice for design­ing axially loaded piles. The seminar included contributions from 17 European countries, each of which provided a synopsis of their respective national design approaches. This paper pays particular attention to the design methods based on laboratory and in-situ test data for both bored and displacement piles.

Jan 1, 2002

By M. N. Shetty, A. C. D. Chaklader

RECENTLY, it has been demonstrated that a considerable densification and interparticle bonding can be achieved if a pressure is applied to a powder compact while the material of the compact is undergoing either a decomposition reaction' or a polymorphic transformation.' The term "reactive hot pressing" has been coined to identify this process in which a phase change is combined with pressure to achieve interparticle bonding. This process is based on a principle which postulates that there is an enhanced reactivity and mobility of the molecular species at the phase-transformation temperature and this effect is utilized for interparticle bonding in powder compacts. This note summarizes the results obtained in an attempt to utilize this technique to produce ceramic-metal composites. In this case, a decomposition reaction of a compound (which after decomposition yielded an oxide) was used to achieve interparticle bonding in ceramic-metal composites. The reactive hot pressing was carried out in a Phillips induction heating unit, using either a graphite or a high-temperature steel die which functioned as both the susceptor and the hot-pressing component. The die was heated to the desired temperature in a helium atmosphere. All cermets produced by this technique were based on alumina as the ceramic phase. Different metal phases such as iron, copper, and chromium were used to study the effect of varying the metal phase on the properties of the composite. a Mono-hydrate (Boehmite) was mixed with different proportions of metal powders (-325 mesh) in dry condition in a mortar and pestle. No special precautions were taken for proper mixing. The mixtures were then compacted into a cylindrical form having an approximate dimension of 1 cm in diameter and 1 cm in height. For this compaction an ordinary

Jan 1, 1965

By Maurice E. Bailey

The purpose of this study is to determine worker acceptance of modified mine equipment at various intervals during a twelve month period. A survey instrument was administered to the workers by two experienced miners in four interviews. All four interviews showed a significant positive response to all modifications, except the small size of the cab of the shuttle car; however, the small size produced significant negative responses with respect to comfort in each of the four interviews. Initially, (interviews one and two), there were significant negative responses with respect to manufacturer receptivity to operator suggestions and program management follow-through on operator suggestions; however, the third and fourth interviews showed no significant negative responses with respect to these items. Likewise, there were significant neutral responses in the first two interviews; however, the third and fourth interviews showed no significant neutral responses with respect to these items.

Jan 1, 1975

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 Mark A. Williams

"This paper was originally intended to be a presentation of a case study of two surface bituminouscoal mines in the southern Appalachian coal fields located within five miles of each other. These mines were nearly identical in every aspect from geologic setting to equipment application. Althoughrepresentatives from each mine desired to participate in the preparation of this paper through support in providing background information and in review and editing, it was later concluded that, due to the environmental sensitivity associated with each mine, it may not have been a good decision to present this case study in a public forum."

Jan 1, 1994

By Peter D. Bell

The paper describes the geology of the gold deposits of the Yanacocha district, Northern Perú. The Yanacocha District is located 20 km north of the city of Cajamarca, whose deposits are located in the Andes of norther in Perú. Gold production may have occurred as early as Incan times, but modern exploration that began in the 1960’s targeted only copper and silver. Current mining is entirely by open pit methods with heap leach recovery. Production in 2003 was from the Cerro Yanacocha deposit and the La Quinua fluvioglacial deposit. La Quinua is not discussed in detail in this report. However, Yanacocha is described as a high-sulfidation epithermal deposit occurring in pyroclastic rocks. The success of Yanacocha has made this type of target among the most sought after by exploration companies worldwide. The important characteristics of the geology of Yanacocha are reviewed below, along with some specifics of exploration techniques used in the district.

Sep 12, 2005

By Reid K. J, Restarick C. J

The breakage and flow characteristics of quartz, ground as a minor constituent with calcite in a continuous wet ball mill, have been determined by carefully controlled grinding tests.A mathematical model, combining the simple functions which describe these characteristics, has been used to predict both steady state and non steady state results.The calculated results are compared with experimental data.

Jan 1, 1966

Modem mineral exploration and development takes place within a data-rich context underpinned by a wide range of data acquisition, processing and interpretation technologies. This leads to requirements for consistent and explicit methods by which the relative risks - or success probabilities - of exploration programs can be assessed and communicated. Bayesian risk assessment methods are outlined which provide a starting point for this more rigorous approach to exploration investment.   Effective governance of information technologies becomes a core function of the modem competitive Board. As such it becomes a component of any business audit and any assessment of the quality and success potential of a company. Limited data however suggest that the average Board may be under-represented in this increasingly critical skill area.

Jan 1, 1997

By A. Adu-Acheampong

The Mid-Tennessee Zinc (MTZ) mines, comprised of the Gordonsville, Elmwood, and Cumberland sites, last operated 4 years ago and are undergoing rehabilitation to begin production in 2008. The mines utilize a random room-and-pillar mining method that results in complex ventilation networks. Upon decommissioning, the mechanical ventilation units were removed and disposed of and several shafts sealed. In an effort to re-open the mines and operate in compliance with imminent Mine Safety Health and Administration (MSHA) diesel particulate matter (DPM) regulatory limits of 160TC µg/m3, a new ventilation system was required. The new ventilation system was developed primarily based on the diesel equipment required to meet production. Particular emphasis was placed on the DPM, diesel equipment utilization, main fan sizing, and fan locations to enable the mines to meet MSHA?s ventilation requirements in a cost efficient manner.

Jan 1, 2009

By Madgwick J. C, Ralph B. J

A method for the determination of microgram quantities of uranium in leachates from low grade uranium ores is described. Solubilized manium is purified by transfer to an organic solvent by a selective solvent extractionprocedure using tributyl phosphate, iso-octane, and aluminium nitrate. The organic phase is mixed with scintillation fiuors in toluene and the radioactive decay determined in a liquid scintillation counter. The method is sensitive and reproducible in the range 3-30 µg uranium.

Jan 1, 1978

By E. H. Myrhaug, K. Aasly, T. Malvik

Six different types of quartz and quartzites used as raw materials by ferroalloy plants have been investigated with respect to their thermo mechanical properties. In order to investigate the effect of the thermal shock caused by the rapid heating of quartz when it enters the furnace, the following techniques have been used for both in situ investigations and investigations of pre-heated quartz: -Heating stage microscopy for in situ observation of heating effects. -Shock heating of quartz in an induction furnace An optical microscope-mounted heating stage was used for in situ observations of the microscopic effects of heating up to 1300 ºC. The effects of heating were observed at different temperature intervals in different samples. The main temperature intervals were below 573 ºC and above 1000 ºC. The cause of the observed effects is interpreted as fluid inclusion decrepitation for T<573 °C and structural implications (micro cracks, grain boundaries and remaining fluid inclusions) at T>1200 °C. Shock heating of the samples was carried out in an induction furnace to 1300 ºC for ten minutes. The effects of the heating were studied with different techniques such as direct observation during and directly after heating, optical microscopy and XRD. Combined transmitted and fluorescence light microscopy shows that the heated quartz show an opening of the grain boundaries and evenly distributed micro cracks that were not present in the unheated reference samples. In some of the heated samples, weak generation of cristobalite was detected by XRD.

Jan 1, 2007

By Ken Dyck, Chuck Edwards

"Cameco's McArthur River is the world's largest high grade uranium mine. Production started in late 1999. Cameco carried out the engineering design and construction management for the McArthur River project, including all aspects of mining, ore handling and ore transportation. The ore composition was expected to vary dramatically (0 to 30% U3O8; 0 to 25% clay; etc). To cope with the composition swings, sizing screens were selected to provide classification in the grinding circuit. The grinding circuit started up close to the design to provide minus 500 micron slurry. The 50% solids (wt) ground ore slurry proved to be difficult to transport to and process at the Key Lake Mill. Slurry containing high concentrations of high density pitchblende (about spgr 8.0) and low concentration of stabilizing clays, would settle in containers. Ore transport efficiency to Key Lake was found to be unacceptable.A test classification cyclone was installed in the grinding circuit at McArthur River early in 2002. The cyclone operating parameters were not typical, but the cyclone was made to work very successfully. Transportation efficiency to Key Lake increased due to more stable slurry. Preferentially ground (fine) pitchblende particles were easier to leach at Key Lake. The radiation exposure for operators and maintenance personnel to handle the more stable slurry was also reduced.The classification sizing screens were removed from the McArthur River grinding circuit and replaced by permanent classification cyclones late in 2002.INTRODUCTIONThe McArthur River mine and Key Lake mill operations are located in northern Saskatchewan, approximately 650 and 720 kilometres from Saskatoon, respectively. Figure 1 is a location map. McArthur River is the world's largest, high-grade uranium mine, with a production capacity of 18.7 million pounds U3O8 annually. (Rosner and Edwards 1998, Dyck 2000, Jamrozek 2000, Rodgers 2001) Proven and probable reserves are more than 473 million pounds U3O8. McArthur River ore, grading on average 21% U3O8, is milled at Cameco's Key Lake operation, 80 kilometres southwest by road. McArthur River production began in December 1999."

Jan 1, 2004

By Norman O. Lotter, Virginia Lawson, Mika Muinonen, Dominic Fragomeni, Jorge F. Oliveira

Development of metallurgical flowsheets from drill core to production of finished metal involves two main domains: process mineralogy to sample the ore and develop a successful flowsheet producing saleable concentrate; and extractive metallurgy to convert that saleable concentrate to finished metal. Effective flowsheet development for a new or brown-field concentrator and processing facility is essential to project schedule and return on investment. Over the last decade in particular, the integration of geology, mineralogy, sampling, and mineral processing have empowered the development of an improved practice in flowsheet development. The use of geometallurgical units as a basis for best-practice sampling delivers representative study material to the laboratory. Modern automated mineralogy characterises the whole rock assembly and paymetal mineral hosting, to address downstream process implications. Batch scale flotation testing then uses this information to design and perform well-focused strategies. At early stages of the project, the Extractive Metallurgy team is engaged to determine processing constraints or other economic drivers in conversion of the saleable concentrate into finished metal. The team evaluates available technologies, assesses the impurities and key properties of the given concentrate. In many cases, changes to mineral processing flowsheet are required to maximize value per tonne of concentrate. Site conditions, availability of infrastructure, energy and power all play an important role. Modern metallurgical simulation tools such as FactSage™ and METSIM™ can quickly define the appropriate test program for each process. Bench scale testing and appropriate scale of piloting can confirm simulations and provide design criteria. A case study demonstrates how effective use of these tools and a multidisciplinary team can accelerate flowsheet development, while reducing costs and ensuring that the designed processing facilities maximize project value with minimum risk.

Jan 1, 2014

By Masaki Kitazume

Deep mixing method, in-situ admixture stabilization technique, has been developed and adopted for on land and marine construction works in Japan. The geotechnical design procedure of the method has been standardized in Ministry of Land, Infrastructure and Transport Government of Japan for port and harbor facilities, which includes the block type and wall type improved grounds for foundation stability, settlement reduction purpose. This procedure is based on the allowable stress concept, in which the induced stresses within the improved ground are confirmed to be lower than the allowable strength in the internal stability calculation. This procedure has been cited by several organizations to establish their standards. The Ministry has a plan to introduce a reliability based design for marine construction works in 2006, in which the design procedure on DM improved ground will also be modified to the reliability based. In the new design procedure, the average and variation of soil parameters and external loads are incorporated by partial safety factors to investigate the stability of improved ground. According to the plan, the author has been studied the design procedure and the magnitude of partial safety factors, and has established a preliminary draft of the standard. This draft will be brushed up through comparing the current design procedure. In this article, the design concept and design procedure of the method are briefly described.

Jan 1, 2004

By Ashley P, Neale T

Alluvial gold was discovered on Sudest Island in 1888, and by 1893, an official production of 10 000 oz had been won by expatriate miners from shallow alluvial and colluvial workings. Hardrock sources were located and while one was developed at Mt Adelaide, production is unknown. Sudest Island comprises mostly phyllites and lesser coarse grained rocks which are cut by metamorphic quartz veins and basic (locally shoshonitic) intrusives. Sheared and altered basalts and serpent- inites represent are believed to be elements of an ophiolitic suite inferred to be associated with metamorphic core complex development and thus similar to tectonic environments on Misima and the D&apos;Entrec- asteaux Islands. No epithermal-style quartz suggestive of a target similar to that on Misima Island has been identified on Sudest. A hardrock source for the alluvial and colluvial gold is interpreted to be metamorphic quartz veins similar to those in the Bendigo- Ballarat Zone of central Victoria, possibly remobilising gold derived from the meta- sedimentary and meta-igneous rock pile. The present focus is on development of a small scale alluvial gold mining operation in conjunction with exploration for hardrock targets. This latter programme remains at a reconnaissance stage.

Jan 1, 1991

By Antonio A. Cristóvão, Alexandre Pinto

"Abstract Deep foundations of buildings using driven ductile iron micropiles TRIM solutions, leads to recognized advantages, from technical, schedule and economic points of view. High production rates together with the possibility of using conventional equipment, duly adapted, confer this solution a high versatility.The aim of this paper is to describe the main design criteria adopted for the foundations of the Church ""Nossa Senhora dos Navegantes"" building in Lisbon - Portugal. In addition, results of a full scale load test carried out at site are presented, confirming the adequacy of the solution to the geological and geotechnical scenario, which is characterized by the proximity of the Tagus River Basin as well as the presence of heterogeneous landfill material and alluvial layers of soft clay (muds).1. INTRODUCTION Located on the right bank of the Tagus River, in Lisbon, the new Church building of ""Nossa Senhora dos Navegantes"", patroness of fisherman and navigators, with three or four upper floors, is surrounded by a school and by new residential buildings.The Tagus River basin is known by its alluvial soft soils, achieving, in certain areas, more than 50m meters depth, challenging the construction of new facilities due to the significant unfavorable geotechnical conditions.With a modern an unusual architecture, allusive to the ships used by the Portuguese navigators, the building has a reinforced concrete structure, with one basement and three upper floors. A bell tower with about 40m high, emerging from the structure, marks the landscape with the presence of this religious building (figure 2).For all the reasons previously described, geotechnical engineers play a crucial role on the design of valid foundation solutions, from both technical and economic point of view. Ideally, the solutions adopted should be supported by full scale load tests, performed at site, so that design assumptions could be verified and adjusted on time."

Jan 1, 2014

By J. E. Nesset, J. A. Finch, Rosenblum. F., S. Somot

"In a previous presentation at the CMP, evidence was shown for the formation of hydrogen sulphide (H2S) in self-heating experiments on pyrrhotite-rich samples (Somot and Finch, 2006). Oxidation of H2S is strongly exothermic leading to the proposition that H2S is playing a key role in the self-heating process. Subsequently, tests in two weathering apparatus (I and II) were run under varying oxygen levels to further examine conditions leading to self-heating. To characterise their resulting self-heating capacity the samples from the weathering tests were subjected to a modified Stage B test using the self-heating apparatus developed by Rosenblum and co-workers (Rosenblum and Spira, 1995; Rosenblum et al., 2001). Results showed highest self-heating after weathering occurs under low oxygen conditions, supporting the H2S hypothesis. It was observed that highest heating rates are not directly related to highest weight gains of samples.INTRODUCTION“Sulphides” refer to several types of minerals containing sulphur in its lowest oxidation state of - 2. Self-heating is the spontaneous heating of a material without external heat input. It is well established that some sulphides will self-heat on exposure to moisture and oxygen (Farnsworth, 1977; Good, 1977; Rosenblum et al., 2001; Wu and Li, 2005). This process is highly exothermic and if the heat generated is not dissipated, combustion may occur when the temperature reaches the ignition point of the sulphide (typically 350-400 °C). The hazards of sulphide self-heating range from handling hot material, to sulphur dioxide release, to fires. The literature documents self-heating incidents underground, on ships and trucks transporting sulphide concentrates, and in mine waste (tailing) disposal areas (Stachulak, 1990; Lukaszewski, 1969; Headley et al., 1977). Lukaszewski (1969), Farnsworth (1977), and Good (1977) note that sulphide minerals can act as fuel to promote underground mine fires. Based on such findings, sulphide minerals could become classified as hazardous materials, making transport of concentrates and storage of mine waste subject to stricter and more costly regulation. The problem is one the industry is keen to avoid."

Jan 1, 2009