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By Mario Samamé Boggio

El presente texto describe un concepto sobre la futurología o la ciencia que estudia el desenvolvimiento de la civilización en su proyección hacia el futuro y su relación con la actividad minera. Así también se revisa cómo se constituye la Sociedad Anónima y con ella el germen del sistema capitalista en minería. De otro lado, se describen los recursos mineros y el rol de de la ciencia y tecnología aplicados en el continuo perfeccionamiento de sus métodos y así obtener suficientes materias que satisfagan las demandas de los sistemas puestos en funcionamiento.

Sep 1, 1974

By David N. Montgomery

The characteristics of a closed cavity acoustic coupler were measured. Various configurations were investigated to determine their feasibility for use in a portable audio dosimeter calibrator.

Jan 1, 1976

By H. Somekawa

The fracture toughness and deformation structures an AZ31 magnesium alloy processed by equal-channel-angular extrusion (ECAE) were investigated. The average grain sizes of as-ECAE and annealed-ECAE alloys were 4.0 and 16.3 µm, respectively. The plane-strain fracture toughness, Kip, in as-ECAE and annealed-ECAE were estimated to be 27.3 and 23.5 MPam1/2, respectively, by stretched zone analysis. The fracture toughness indicated higher value with grain refinement. From optical microstructural observations in samples after fracture toughness tests, although deformation twins were observed in annealed-ECAE, no deformation twins were observed in as-ECAE. From TEM observations, the dislocations on basal and non-basal planes were activated in as-ECAE. With grain refinement, the activations of dislocations on both basal and non-basal planes were possibly related to the reduction in formation of deformation twins in as-ECAE. In addition, in comparison with direct extruded process, ECAE process was more effective method to improve the fracture toughness in magnesium alloys.

Jan 1, 2006

By Terry J. Briggs, Ian J. Kelso

"Abstract- The Century mine in northwest Queensland,Australia, is a major sediment-hosted zinclead- silver orebody, located within the western Mount Isa Basin. Stratiform, carbonaceous shalehosted mineralization is developed within Proterozoic shale and siltstone sequences of the Lawn Hill Formation. CRA Exploration Pty Ltd (CRAE) discovered the Century deposit in 1990 and open pit mine development commenced in 1998 under the ownership of Pasminco Century Mine Limited (PCML). The deposit contains an identified mineral resource of 105 Mt @ 12.1% Zn + 1.7% Pb + 46 g/t Ag (Broadbent and Waltho, 1998) which is currently being mined at a rate of 5 Mt/y.In December 1998, an exothermic reaction was observed between explosives spilt onto shale drill cuttings from a blasthole. This reaction is referred to as ‘reactive ground’ and has the potential to cause premature detonation of explosives in a charged blasthole with catastrophic consequences. The incident led to a subsequent geological and geochemical assessment of the different rock types at the Century deposit and their potential reactivity with ammonium nitrate-based (AN) explosive products. This assessment was conducted in an attempt to characterize zones safe for blasting with uninhibited AN-based explosive products. A direct result of this study is a set of procedures outlining the use of different AN-based explosives in areas defined as potentially reactive or non-reactive for the different lithologies present. Black shales contained in both the waste and mineralized sequences contain the sulfide mineral pyrite (FeS2), which is thermodynamically unstable with AN contained in commonly used explosives. The potential reactivity of partially weathered pyrite can ultimately result in the decomposition of an AN-based explosive. It was determined that only pyritic black shales showed any potential to react with AN, irrespective of their position in the stratigraphic sequence. Other lithologies present at Century, including Proterozoic sandstone and Cambrian limestone, are classified as non-reactive with AN. This is a geological risk management situation present at the Century mine."

Jan 1, 2001

By M. Kanefsky

Two channel polarity coincidence and polarity difference statistics are analyzed. The signal, common to both channels, consists of sinusoidal bursts where the exact frequency of the signal is nearly known, but other parameters such as amplitude, phase, and pulse starting time are unknown. The noise inputs are dependent, narrow band, Markov processes. It is shown that the performance depends not only on the signal uncertainties, but on the precise shape of the cross-correlation functions between the noise in-puts. By using two polairty difference statistics in addition to the polarity coincidence statistic, it is shown that the decrease in performance, as well as the cost of hard limiting due to correlated inputs, can be made small.

Jan 1, 1981

By Cledwyn Mangunda

Mining operations generate Acid Mine Drainage (AMD) that poses a significant threat to the natural environment. AMD treatment using Ca(OH)2 leads to the precipitation of a sludge dominated by a mixture of ferri-oxyhydroxides. This sludge has poor dewatering tendencies and is deposited in landfills with potential for metal remobilization. This study investigated the dewatering behaviour of a precipitate formed during elevated temperature treatment of a primary, pre-settled sludge from the neutralisation of aqueous acidic Fe2(SO4)3 and Ca(OH)2 solutions in an MSMPR reactor. The resulting treated precipitates were analysed for micro-properties, with results showing that an increase in the secondary reactor temperature from 25 °C up to 50 °C led to an increase in mean particle size, a decrease in the number of particles and improved dewatering behaviour at a ferric concentration of 300 mg/L. This was ascribed to the attainment of a circum-neutral surface charge that favoured agglomeration and a change in micro and nano-structure that allowed for better water passage.

By Hal H. Engel

This publication was written in response to numerous requests for information about the Federal Bureau of Mines' "Demonstrated Lecture on Flame Propagation and Permissible and Explosion-Proof Electrical Equipment." The requests came principally from: (1) Persons wanting to know more about the demonstration before requesting it for groups they represented; (2) persons wishing advance information to help publicize a meeting where the demonstration was to be given; and (3) members of audiences desiring something to help them remember the salient points, facts, and figures presented during the lecture and demonstration. The purpose of the demonstration that accompanies the lecture is to show: (1) Variations in flame speed and pressure at various percentages of flammable gas within the flammable range; (2) effect of flame speed on the "pressure piling" within the area confining the mixture; and (3) the application of flame speed and pressure piling to the combustion of surrounding gas and to the design and maintenance of electrical equipment used in hazardous locations.

Jan 1, 1960

By L. G. Closs

Gold continued to be the primary focus of minerals exploration worldwide during 1995. Other targets, though, included primary diamonds and base metals, especially copper deposits amenable to solvent-extraction/electrowinning (SX/EW) processing. The discovery of nickel, copper and cobalt at Voisey Bay in Labrador, Canada was an unusual surprise. Meanwhile, exploration geochemistry continues to evolve to meet new challenges. The major event in this category during 1995 was the17th International Geochemical Exploration Symposium (IGES) held in Townsville, Queensland, Australia in May. The meeting was sponsored by the Association of Exploration Geochemists, which celebrated its 25thanniversary of service to the mineral industry, and the Economic Geology Research Unit of James Cook University, Townsville.

Jan 1, 1996

By M. W. Von Bernewitz

Corduroy is used for saving gold in small Land large milling plants throughout the world. Investigations by the Metallurgical Division of the Bureau of Mine indicate that corduroy blankets, used with or without a trap or jig in the mill classifier circuit, often are effective in concentrating gold and sulfides, especially if the gold does not amalgamate readily and if not enough sulfides are present to warrant the use of a shaking table, flotation cells, or cyanide plant. Most cold-mining countries include several or many small miner, that produce siliceous ores low in sulfides and gold, which can easily be amalgamated or caught in traps or jigs or on corduroy and shaking tables. At these mines the ore is crushed by stamps or bill mills, and the flow sheets include plates, flotation cells, and cyanide treatment, yet probably nearly as much of the pair minerals may be recovered by the less expensive plant. A well-known western maker of mine and mill equipment asserts, as the result of considerable observation of installed plants, that old and other valuable minerals should be caught as soon as they have been released by a mill, end recommends jigs to do this. A supplier of corduroy has informed us that at some mines this material is being replaced by jigs that catch gold as fine as 400-mesh. But for the small operator, inexpensive equipment such as a corduroy table may be better adapted and give a good recovery of gold and associated minerals.

Jan 1, 1939

By Yuanyuan Wang, Hong Li, Xueting Liu, Hao Bai, Kang Zhou

"Phase change materials are widely used in efficient utilization of energy and new energy technology. Especially, more attention has been paid to composite phase material, which is applied on architectural energy-saving and efficient working fluid. In this paper, stearic acid-silicon dioxide composite material was prepared by sol-gel process from tetraethyl orthosilicate (TEOS) and stearic acid (SA). The material was investigated by Field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR) and Differential scanning calorimeter (DSC). The FE-SEM results show that 3D-grids of silicon dioxide were formed clearly and SA was encapsulated in the silicon dioxide shell. The FT-IR results show that there were no chemical reactions between silicon dioxide and SA, which is the chemical property of the composite material, is stable. The DSC results show that the composite phase change material has favorable heat capacity. This material is expected to be used to make a cooling working fluid.1. IntroductionEnergy thermal storage becomes increasingly prominent issue in recent years, because thermal storage has been used in many aspects, for example, it can be added into building materials to improve heat conditioning. Another potential application of thermal storage materials is that the intermittent waste heat can be collected and recycled effectively by using the thermal storage facility. Thus, energy thermal storage plays a significant role in conserving available energy and improving its utilization [1]. Energy thermal storage includes sensible heat storage and latent heat storage. The latent heat storage has great heat density with a constant temperature during the phase change process [2-5]. Large quantities of latent heat storage will be absorbed and released when phase change takes place. Based on the former researches, some phase change material (PCM), such as fatty acid and paraffin waxes, has been proved to have high latent heat storage capacity and appropriate thermal properties [5-6]. However, using the PCM in energy storage systems directly is restricted, e.g. some properties of organic PCM, like form-stability and thermal conductivity, are not good enough to use. Meanwhile, almost all the inorganic PCMs are corrosive and most materials may cause sub cooling and segregation [7-9].The other problem is that the leakage when the temperature reaches the phase change point. Therefore, encapsulated composite phase change material (CPCM) emerged in order to solve the problem of leaking out, minimize the sub cooling and prevent phase segregation. [10-13] However, the easy flammability of fatty acid also has hindered the development of PCM. Accordingly, it has been found out that silicon compounds are environmentally friendly promising substitutes for halogen-containing flame retardants. Especially, silsesquioxanes are excellent in the flame retardancy. So CPCM can be encapsulated with SiO2 acting supporting material."

Jan 1, 2014

By James R. Aggson

This Bureau of Mines report describes floor heave ground control problems that have been encountered in a new underground coal mine in West Virginia. Previous experience in the coal seam, the results of physical property investigations, and in situ rock stress determinations are discussed. The apparent cause of the ground control problems is the existence of a high, biaxial, horizontal stress field coupled with a floor member that has time-dependent deformation characteristics, A theoretical analysis of the failure process is developed. The analysis is assisted by finite element techniques. Mine design recommendations based on this analysis are presented.

Jan 1, 1978

By G. S. Pauley

Paper presented at a meeting on: Artificial intelligence in the minerals sector, held in Nottingham, UK, 20 April 1993 (original title: Case-based reasoning can be a catalyst for improvement). A new computer software technology known as Case Based Reasoning (CBR) can be used to produce small decision support systems that are economically viable. This is because the knowledge that they contain can be owned and maintained by their users. A CBR tool has been used to perform a pilot study with Anglesey Aluminium Metal Ltd. The results are encouraging. They suggest that a combination of CBR and participative design and implementation techniques (such as Checkland's Soft System Methodology) can achieve sustainable improvement in mineral processing functions. An explanation is presented of why traditional, rule based systems are often an ineffective way to implement support systems. It is shown that CBR may provide an appropriate technology solution. Methods of achieving sustainable benefit are indicated. The pilot study with Anglesey Aluminium Metal is used as a practical illustration of the development of a CBR application. A review of potential application areas and some observations about the implementation are presented

Apr 1, 1994

By W. D. Mcmillan

The Dempsey tract in Washington County, Mo., had a small production of lead-zinc ore from shallow workings. Old dumps from early-day lead mining contain about 25,000 tons of ore averaging about 3 percent combined zinc and lead. Because of the urgent war requirements for lead and zinc, the Dempsey property was examined by Otto Ruhl, formerly an engineer of the Bureau of Mines in August 1942 and selected for further investigation by churn drilling twenty holes totaling 1,309 feet were bored in the fall of 1943. The results of the work are presented in this paper.

Jan 1, 1948

By Joy Sandberg

The 1989 mining industry compensation survey done annually by the Denver-based Mountain States Employers Council shows the "average" or "typical" employee in the mining industry is projected to receive an increase of 3.9% to base pay in 1990, compared to a projection of 4.1 % for 1989. According to MSEC, the actual percentage increase to base pay has continued to decline since 1980. A review of pay increases since 1980 shows the highest average increase was 11%, granted in 1981. Since 1981, there has been a steady deceleration through the decade. While 1989 final figures are not available, 1988 numbers might indicate a reversal of this trend. In 1988, the average employee actual increase was 3.8%. That was 0.7% higher than the 3.1% projection. This may be significant as actual increases have been lower than projections since 1982. Chart A shows the pattern of projected vs. actual percent increases in pay since 1980.

Jan 1, 1990

By D Yan, D Connelly

Beneficiation of magnetite is an integral part of the future of iron ore processing. Historically, the focus of Western Australian producers has been on exporting direct shipping ore (DSO) namely haematite. The future for new DSO resources is limited so companies are changing their emphasis into processing the very large, undeveloped magnetite ores in Western Australia (WA), using beneficiation to produce shippable magnetite concentrates. These magnetite resources require higher cost processing techniques such as fine grinding and beneficiation to produce saleable concentrates. This distinct difference, from the DSO ores, has led to the development of a number of new technologies. This paper reviews: the different techniques used for magnetite beneficiation and provides some case studies in the WA industry; the use of mineral liberation analysis (MLA) to describe the nature, grain size, occurrence and associations of the mineralisation;the consideration of coarse cobbing as a critical upgrading; the application of high pressure grinding rolls (HPGR) to save energy; how the field of magnetic separation has resulted in new machines with higher field strength (SLon Separators); ultra fine grinding requirements of magnetite concentrates; andthe application of reverse flotation to reduce silica in the concentrates.

Jan 1, 2009

By G. L. Smith

As the Platinum mining industry expands in the Eastern Limb of the Bushveld Complex it is increasingly evident that a major constraint to development is a lack of appropriate infrastructure. Of critical concern are water resources and spatial development / infrastructure. This paper identifies the context for infrastructure development in the Eastern Limb and two solutions that have evolved in the areas of water supply and spatial development. INTRODUCTION In an economics context, infrastructure is considered to be the structural elements of an economy which allow for the production of goods and services, without themselves being part of the production process. Despite the lack of a specific definition, infrastructure has largely become understood as to comprise road and rail transport systems, public transport systems, airports, public educational facilities, water supply and water resources, wastewater management, solid waste treatment and disposal, electric power generation and transmission, telecommunications and hazardous waste management systems. Critically it is important to understand that infrastructure not only comprises these physical elements but also the operating procedures, management practices and developmental policies that facilitate the effective utilization and development of the infrastructure in response to societal demand.

Jan 1, 2008

By P. M. Wiltcher

The construction of a deep structural slurry wall in a restricted city centre location is always a challenging prospect. However, when the city is London and the site is bounded on two sides by high level canals and a main traffic highway on the third, the challenges are greater than usual. The paper discusses the design considerations required by the principal contractor to accommodate a single high level lateral support, value-engineered, bottom-up construction technique and the impact this had on the design detailing and construction of the slurry wall panels. This paper discusses the logistical challenges successfully overcome during the construction of 65,000sq ft of 40inch thick, 80ft deep structural slurry wall in the City of London. The paper reviews the benefits gained from using the state-of-the-art hydraulic grab and rotator system. Technological advances in computer instrumentation and real time monitoring were utilised to assist the grab operators in consistently delivering deviational control during excavation better than 1:200. With working space always at a premium on construction sites, the need for high quality, pre-fabricated reinforcement cages has never been greater. This paper reviews the argument for off-site fabrication of reinforcement members.

Jan 1, 2006

By G. Austin Schroter

ALTHOUGH there is now an extensive literature on the bleaching clays, not a great deal of material is to be found concerning the geological fea-tures of these deposits and their bearing on problems of exploration and development. At the same time, chemical and crystallographic research on the clay minerals during the past few years has laid a suitable founda-tion upon which to base conclusions of economic value drawn from field observations. All of the criteria and deductions herein presented are based upon extensive field work by the senior author, both in the United States and Canada, and when subjected to the ultimate tests of development and exploitation they have held up remarkably well, despite the fact that many of these conclusions apparently have not been reviewed in the litera-ture heretofore. The nomenclature of the bleaching clays is rather confusing in the light of present-day commercial standards and has even led to litigation.76 The old term "fuller's earth" is largely based upon trade usage and the definition of the term therefore is dependent upon the changing standards of commerce. For statistical purposes the Bureau of Mines81 classes as "fuller's earth" all natural bleaching or filtering claylike materials that possess high adsorptive capacity without previous chemical treat-ment or activation. Conversely, the so-called activated or acid activated clays are now generally recognized as any clay mineral or mixture of the clay minerals whose adsorptive capacity has been developed to commercial standards by chemical or physical treatment. Therefore, without attempting to propose any additions to the nomen-clature of bleaching clays, this paper will refer to naturally adsorptive clays and activable clays, respectively, for the two types indicated.

Jan 1, 1940

By Milo Krejci

(Butte Meeting, August, 1913.) THE plant and quarries of the Inland Portland Cement Co. are located at Metaline Falls, Wash., about 128 miles north of Spokane, on the Pend Oreille river, and within 10 miles of the Canadian border. The plant is one of a chain of cement plants controlled by the Lehigh Portland Cement Co., of Allentown, Pa. Work on this plant was commenced in June, 1910, and was completed in April, 1911, but on account of some delays in 'the construction of the power plant, the works were not put into operation until August, 1911. Since then it has been in continuous operation and has furnished the Inland Empire with a high grade of cement. Fig. I is a view and Fig. 2 is a plan of the works. Water Power Development.-The source of the water supply for the hydro-electric plant of the Inland Portland Cement Co. is Sullivan lake, a body of water approximately 5.5 miles long and 0.5 mile wide, situated in the Kaniksu Forest Reserve. A wooden crib dam was installed so as to raise the elevation of the lake 25 ft., and the additional storage capacity was taken up by the diversion of Sullivan creek into the lake by means of a wooden flume, 0.25 mile long, 6 by S ft. in cross-section, and a ditch 1,200 ft. long. The water from the lake follows the natural water course to an intermediate storage reservoir, which was created by the construction of an earthen dam. This pond wits used in connection with the saw mill which was installed at this point. Besides the earth dam, there was also built a crib, at the point shown in the sketch map, Fig. 3. This crib dam is 35 ft. high. From this point the excess water follows the natural course of Sullivan creek to the Pend Oreille river.

Jan 7, 1913

By S. K. Asunmaa, W. D. English, N. A. Tiner, W. A. Cannon

This paper discusses the reaction of metal surfaces with fluorine. Fluorination reactions result in the formation of metal fluoride films which are "passive" toward further reaction of the metal with fluorine. These films are very adherent, and do not easily detach from the substrate metal by mechanical flexing or thermal shock. Exposure of passive films to a humid atmosphere produces hydrated metal fluorides which cause secondary fluorination reactions upon reexpo-sure of the metal surface to fluorine. The surface films formed range from 10 to 30A in thickness and they pow at the expense of surface oxide films. The apparent film formation is completed rapidly in 15 to 30 min on stainless steel and nickel surfaces. On copper and on Monel surfaces, the film at first grows rapidly, then increases slowly over an extended period of time. Passive films are formed at all fluorine pressures in the range from 0.1 to 1.4 atm at room temperature. ALL metals react when exposed to fluorine. These reactions generally produce surface films which consist of metal fluorides. The rate of reaction is largely determined by the extent to which these films are protective. Although there is an extensive literature concerning reactions of oxygen with metals, there are very few investigations reported concerning fluorine-metal reactions. Brown, Crabtree, and ~uncan' investigated the kinetics of the reaction of gaseous fluorine with copper metal which had been freshly reduced in hydrogen. The reaction rate was independent of pressure over the range from 6 to 60 torr. A logarithmic rate law was obeyed in the temperature range from 25" to 300" ~. There was some deviation at higher temperatures which could have been the onset of a parabolic law. The calculated film thicknesses ranged from about two molecular layers, 10A, for 5 hr exposure at room temperature to thirty-five molecular layers for 5 hr exposure at 200" . The authors concluded that no single mechanism could explain all the observations. O7Donnell and spatkowski2 studied the reaction of fluorine with copper at 450°C at pressures from lo to 133 torr. The reaction was found to be pressure -dependent and followed a logarithmic rate law. It was not entirely diffusion-controlled, and fluorine was thought to be the migrating species in the reaction. Miscellaneous metal-fluorine reactions were investigated by Haendler et ~1.~ Reaction products were identified but no rate data were determined. Air Prod- ucts and Chemicals, Inc., have conducted an investigation of reactions between fluorine and various metal powders at room temperature and 85° C. Fluoride film thickness as a function of time of exposure was reported on the assumption that the reaction takes place between fluorine and metal to form the normal metal fluoride. Surface areas of the powders were only estimated so the relative film thicknesses may not be exact. The data showed reaction rates which were generally logarithmic in character, the rate of film growth virtually ceasing after a few hours exposure time for some alloy powders. The effect of moisture on fluoride films was also investigated by measuring additional reaction with fluorine after exposure of passivated powders to atmosperic moisture. The fluorination of iron was studied by 0'~onnell~ at temperatures from 225" to 525" ~ and at pressures ranging from 20 to 200 torr. In all ranges, the reaction followed a logarithmic rate law and was dependent on the square root of the gas pressure. The author concluded that fluorine gas passes through pores in the film. As the film grows, the blocking of pores leads to a rapid decrease in reaction rate; hence a logarithmic rate law is observed. Jarry, Fischer, and Gunther' investigated the mechanism of the reaction of fluorine with nickel at about 600" to 700°C. On the basis of the metallographic examination of fluoride scales growing on the nickel and from separate radioautographic data, it was claimed that fluorine is the migrating species in the reaction. This is in sharp contrast to the growth of oxide films on nickel where it has been shown that nickel ions migrate through the scale to the gas-solid interface to react with oxygen. Few investigations have been reported of the reaction of fluorine with metal oxides. Such investigations should be of great significance for a better understanding of passivation in view of the ubiquitous oxide films on technical alloys. Haendler et al.3 studied the reaction of fluorine with oxides of copper, tin, titanium, zirconium, and vanadium. Copper (I) oxide reacted as follows in the temperature range 150" to 300"~: temperature above 300" ~ was required for the CuO to react to form additional copper fluoride. Ritter and smith7 also investigated the reaction of fluorine with copper (11) oxide. An oxide powder comprised of spherical particles with a fairly high surface area was reacted with fluorine, starting at room temperature and increasing to 100° C over a period of 3 or 4 hr. The initial reaction was slow until the fluoride film thickness reached about to or 15R at which time the reaction rate accelerated, then decreased again. Most of the kinetic data was obtained during this final phase of reaction. The authors conclude that the film grows slowly at first until the stresses developed in the distorted lattice are sufficient to rupture the initial

Jan 1, 1969