Search Documents

By Xiangxi Wu

Longwall and continuous mining are prevalent methods employed by Chinese underground coal operations. The main ground control challenges include roof skin deformation, roof collapse, and outbursts of coal, gas, and water. Microseismic monitoring provides valuable information on rockmass behavior and fracture propagation caused by stress redistribution, active geological structures, or gas build up within the coal strata and the surrounding rockmass. Collecting and assessing seismic data has proven to be an instructive tool for engineers to better assess ground conditions and mitigate seismic hazards associated with mining. The development of intrinsically safe and explosion proof certified seismic monitoring equipment has revolutionized China?s underground coal mines. The use of this technology allows for the optimization of gas drainage at an increased rate of two at a 50% higher purity without any increase in drilling costs. Microseismic monitoring can also be used in identifying seismically active faults and shear zones. This information can be used to assess and revise mining strategies to improve safety and ground stability.

Jan 1, 2012

By Jian Li

Developing the Generation IV nuclear reactor is an international collaborative effort. One of the most promising Gen IV nuclear reactor designs is the supercritical water (SCW) concept, in which the water coolant runs at about 625 oC at the outlet. Under this temperature and high pressure condition, the cooling water is at supercritical state, which poses significant demand for both in-core and out of core materials. High-temperature mechanical properties, corrosion resistance and radiation damage are some of the key challenges. At present, no single commercial material can meet all the requirements of the severe SCWR conditions. Corrosion experiments per-formed under SCW condition yield various kind of corrosion modes, some are very challenging to characterize using conventional techniques. A combination of various advanced characterization techniques proofed to be essential to understand the root cause of materials? degradation.

Jan 1, 2010

By W. Chae

The influence of solution ionic strength (IS) and electrolyte valence on the flotation behavior of malachite has been investigated. The microflotation tests were conducted over a range of solution IS (1?300 mM) at a constant speed (340 rpm), pH (9.5), flotation time (10 min), and sodium oleate dosage (5.3×10-7 moles/g). The size of malachite ranged from 45 to 53 µm, and two different types of electrolytes (NaCl and CaCl2) were employed. Electrophoretic mobility was also measured over the same IS range employed in the microflotation study. Overall, strong coupled effect of solution IS and ion valence was observed. Specifically, the flotability of malachite increased with increasing IS in the presence of monovalent cation (Na+) while the flotability increased up to 30 mM and decreased with increasing IS in the presence of divalent cation (Ca2+). Notably, the flotability of malachite was greater with the presence of Na+ compared with Ca2+ under high IS conditions (IS>30 mM). Consistent trend for Na+ versus Ca2+ was observed from the flotation results with different SO dosages. The characterization and flotation results suggested that the trend was likely attributed to the increased unfavorable interaction between malachite and bubble via the charge reversal of bubbles and malachite at higher IS in the presence of Ca2+.

Feb 27, 2013

By R. L. Grunes, F. K. Kies, C. D&apos, Antonio

THE several studies concerned with the annealing of thin nickel films have largely been restricted to films of a single thickness.1-4 It is well-known, however, that both physical and mechanical properties depend upon film thickness.5, 6 The strength-thickness relations found in vapor-deposited nickel films in the annealed and as-deposited states, as an example, are at least partially due to the density and arrangement of imperfections within the films.7, 8 For these reasons, the annealing characteristics of thin nickel films as a function of thickness were investigated. Electrical resistance was chosen to monitor annealing behavior since resistance changes are partially dependent upon defect structure. In addition, the equations predicting film resistivity as a function of thickness are already available.9, 10 Further advantages afforded by electrical-resistance measurements are its adaption to continuous readings during annealing and its relative simplicity. Nickel films were vapor-deposited, at average rates of 60Å per sec, on Vycor substrates held at room temperature in vacuums of about 10-5 torr. Afterwards, deposition-thickness measurements were made using a multiple-beam interferometric technique. A more detailed description of deposition procedures and the interferometer appear elsewhere.7, 8 The four-probe method was employed in measuring electrical resistance since this technique measures film resistance without contributions from lead wires and contacts. Resistance measurements were made before, during, and after annealing to temperatures of 700°C under vacuums of approximately 10-4 torr. Measurements were made every 25°C or more often when necessitated by unusual resistance changes. Cooling and heating rates were maintained at approximately 5°C per min. Typical resistivity vs temperature curves are shown in Figs. 1 through 4. It is apparent from these

Jan 1, 1965

By J. G. Donaldson

Nickel containing less than 0.01 percent of total metallic impurities was produced at the Rolla Metallurgy Research Center of the Bureau of Mines by electrodeposition from purified electrolytes. The first report on this research4 described purification of electrolytes by selective precipitation and by liquid-liquid extraction. This second report describes a procedure: or electrodepositing high-purity nickel from electrolytes purified by passing a nickel ammine solution through a column of an ion exchange resin. The nickel electroplated directly from the ammine solution without further treatment; a titanium cathode and two platinum anodes were used. The nickel deposit was dense, smooth, and adherent, and contained less than 0.001 percent each of cobalt, copper, and iron, and spectrographically detectable traces of aluminum, magnesium, and silicon. Nonmetallic impurities in the nickel metal were carbon and sulfur, each present in concentrations of less than 0.01 percent. The results of several experiments planned to purify solid nickel salts by zone refining are also reported. These salts, after purification, were intended for use in preparing electrolytes for deposition of high-purity nickel. Results were not encouraging so that the more promising ion exchange procedure was emphasized chiefly.

Jan 1, 1962

By W. C. Phalen

The production of salt in the United States divides itself at the outset into two distinct classes…

Jan 1, 1915

Bahrain's oil revenue increased from $337 million2 in 1916 to $378 million in 1977. Despite the increase in value, petroleum receipts made up only 584 of all Government income in 1877, compared with 74% in 1976 and 83% in 1975. Bahrain became an oil producer in 1932 with the discovery of the Awali oilfield, and since that time, the Awali oilfield has produced over 600 million barrels of crude oil. Awali production in 1977 was 21.2 million barrels. Bahrain shares the revenue from the Abu Safah oilfield, located in the Persian Gulf north of Bahrain, equally with Saudi Arabia. Revenue from the Abu Safah oilfield was approximately $179 million or 47% of oil revenues in 1977. Output from the Abu Safah oilfield was 48 million barrels, an increase of nearly 30% over 1976 output. The Bahrain Petroleum Company (BAPCO). the nation's only oil-producing company, was owned 40% by California Texas Oil Corp. (CALTEX and 60% by the Govern¬ment. The Government established Bahrain National Oil Co. (BANOCO) in 1976 to administer the Government's share of BAPCO, oversee exploration concessions, and manage domestic marketing of petroleum products. The Government announced its intention to acquire 100% control of crude oil and natural gas production. CALTEX was to retain complete control of the 250,000-barrel-per-day oil refinery near Sitrah.

Jan 1, 1981

By C. George Miller

"As the influence of governments has become more widely felt, the use of research techniques to analyze policy has increased. Mineral economics, as one of the foundations of mineral policy research, has grown accordingly. Policy research and analysis has been carried out within governments, university departments and the private sector. Each of these institutional environments has characteristics which influence the topics of study, the approach, the methodology and the output of the research. A brief survey of recent research activities provides illustrations of trends and developments occurring within this organizational framework.A radically different organization, the independent research institute, has begun to make an impact on policy research in recent years, and will have an increasing importance in the future. Combining certain features of the traditional research organizations, it nevertheless has important differences which are essential to its effective functioning. An overview of the formation, goals, organization and operation of one such institute is presented."

Jan 1, 1976

By William H. Pomroy

The Bureau of Mines, through a 4-year program of combined in-house and contract research, has developed the necessary hardware and software technology to provide rugged, reliable automatic fire protection for surface mining mobile equipment. One element of this program was a continuing effort to help foster rapid mining industry acceptance of the technology by keeping end user costs reasonable. This report is an analysis of the economic impact of surface mining mobile equipment fires and the cost benefit of utilizing automatic fire protection systems to abate these losses.

Jan 1, 1982

By A. E. Taylor, A. S. Judge, P. T. Lafleche

"Resource development in northern Canada has special requirements which derive from the unique environmental and eco-logical nature of the northern environment. In this paper several case histories in which the Permafrost Research Section of the Geological Survey of Canada (GSC) has participated are used to illustrate how geophysical methods may be used to address some of these considerations. Although some of these examples were developed while examining problems directly related to oil and gas development and transport in frontier regions, such or similar methods also have application to mining problems.IntroductionA critical parameter is the distribution and thickness of permafrost, which in northern Canada varies from being a few metres and discontinuous at the southern limit to thicknesses in excess of 700 m in the Arctic Islands'!'. Figure I is a schematic diagram of typical ground thermal conditions in a permafrost zone. The upper zone is defined by an active layer which undergoes a seasonal freeze/thaw cycle. In the simplest case, the ground remains permanently frozen below the active layer to the depth of the O°C isotherm, which is defined as the base of the permafrost. Water chemistry, pore structure and pore or grain size may cause the base of the frozen ground to be above the permafrost by up to 100 m(2). Ice can be found within the permafrost in the pores of solid rock or sediments, as massive ice within unconsolidated sediments or as ice lenses within fissures in a solid rock mass. The mining technique used in these conditions, whether open pit or underground, can differ considerably from that used in southern Canada. In the high Arctic, for instance, the dry drift method is feasible underground in the permanently frozen host rock. The frozen nature of the wall rocks can obviate water-related problems."

Jan 1, 1987

By AIME AIME

OCTOBER will be western month for the Institute. With meetings at Spokane, Tulsa, Los Angeles, and San Francisco, and with a large number of American Institute of Mining Engineers members and their families in the party sailing out through the Golden Gate to Japan on the afternoon of the tenth, the major activities of the Institute will, for this month at least, be west of the Mississippi. Despite cancellations due to necessity, most of the officers of the Institute will be present and taking part in some one or more of the Western meetings. Prof. Robert S. Richards, our senior past-president, will attend both the Spokane and San Francisco meetings and then go to Japan. President Bradley will preside at the San Francisco meeting and then head the party going to Tokyo. At Tulsa and Los Angeles, the principal officers of the Petroleum Division will be present and active and at all the meetings, directors, ex-directors and -present and past officers will be on the job and keeping things moving.

Jan 1, 1929

By D Craw

Formation of gold-bearing veins in Otago Schist was intimately linked to the structural evolution of the schist belt. The currently-exploited Macraes gold deposit formed in a regional scale shear zone during latemetamorphic uplift of the schist belt. Further exploration for this type of deposit will be facilitated by an increased understanding of the late-metamorphic structural evolution of the schist belt. To this end, a three-dimensional cross section through the Otago Schist has been drawn using structural data gathered at outcrops in a 20 - 40 km wide transect across central Otago. This is the first continuous detailed structural section to be drawn through the belt. The section spans an area from Textural Zone 1 metagreywacke of the Torlesse terrane in the northeast through TZ 4 schist in the central region and across the Caples-Torlesse boundary to Textural Zone 3 schist of the Caples terrane in the southwest. Two different late-metamorphic structural generations are identified in this section: the long-recognised Manorburn Generation, and a new æPoolburn GenerationÆ. The location of the Caples-Torlesse boundary has been refined on this transect by field mapping combined with whole rock geochemistry.

Jan 1, 2001

By Anderson Ayres Bittencourt

O monitoramento de sistemas e ativos de automação sempre existiu de forma rudimentar e descentralizada. A análise desses dados tanto quanto sua obtenção é um desafio para as empresas atuais. Foi a partir deste princípio que nosso projeto foi desenvolvido.Este trabalho tem como objetivo demonstrar a solução de Monitoramento online e preditivo implementada na ArcelorMittal Aços Planos da América do Sul, onde desde o início de sua implementação pudemos capturar benefícios operacionais, melhoria dos processos, otimização, eliminação e/ou diminuição de indisponibilidade de plantas, entre diversos outros retornos que serão apresentados.

Oct 30, 2017

Born, March 28, 1853 Died July 23, 1916 On July 25, 1916, the Board of Directors adopted the following minute and directed that it be entered upon the records of the Board & published in the Bulletin of the Institute, and thereof be sent to the family of Mr. Kirchhoff: Charles Kirchhoff was one of the oldest, most widely known and most highly esteerned members of the American Institute of Mining Engineers. On his return in 1875 from a European course of study, to begin a highly successful professional career, he joined the Institute, then just commencing to acquire both national and international recognition. He became at once, and-for more than 40 years continued to be, its earnest , and active supporter, serving it as Manager, Councilor or Director for terms aggregating 9 years,-as Vice-President for 2 years, and twice as President for a year. During the critical period of the erection of the United Engineering Society's building, and the transfer of the Institute to permanent head-quarters therein, Mr. Kirchhoff was its efficient representative in the United Engineering Society, and on the Building Committee. In 1910, amid the congratulations of colleagues, employees, and innumerable friends, Mr. Kirchhoff retired from active business as Vice- President and General Manager of a great technical publishing company. Yet he sacrificed of his well-earned leisure yet one more year, to serve the Institute as President through 1911.

Jan 9, 1916

By D. S. Burgess

About 100 tests of flammability were carried out with H2, CH4, and CO in mixtures with air using the Federal Bureau of Mines 12-ft-diameter spherical pressure vessel as an explosion test chamber. The LeChatelier approximation gave slightly conservative estimates of the limits of downward flame propagation (onset of significant pressure rise) using the following measured values for the individual gases, in percent: H2, 8.5; CH4, 5.25; CO, 13.0. No justification could be offered for using the LeChatelier law for upward flame propagation limits and indeed reported data suggest that calculated values would not be conservative. The observed upward limit for methane-air mixtures (4.85 pct) was less than the widely accepted lean limit for this fuel; those for lean hydrogen-air mixtures and carbon monoxide-air mixtures did not differ from the lowest accepted values. Diffusional effects on the propagation of single, binary, and ternary fuel mixtures are discussed.

Jan 1, 1982

By H. Hamma, R. Fehrmann, M. Gaune-Escard, G. Hatem, S. B. Rasmussen, K. M. Eriksen

The molten salts M2S2O7and MHSO4, the binary molten salt systems M2S2O7-MHSO4and the molten salt-gas systems M2S2O7-V2O5and M2S2O7-M2SO4-V2O5(M = Na, K, Rb, Cs) in O2, SO2and Ar atmospheres have been investigated by thermal methods like calorimetry, Differential Enthalpic Analysis (DEA) and Differential Scanning Calorimetry (DSC). Fundamental thermodynamic data like temperatures and molar heats of solid-solid transition and fusion, phase diagrams, heat capacities of solids and liquids, heat of mixing, and heats of complex formation have been obtained and are reviewed here. Also EPR spectroscopic evidence of V(IV) complexes and their structure are reported and the results are discussed in relation to the mechanism of SO2oxidation by V2O5based industrial catalysts. Keywords: Alkali pyrosulfates, alkali hydrogen sulfates, vanadium pentoxide, EPR spectroscopy, complex formation

Jan 1, 2004

By G. R. Moulder

A device was developed that measures dynamic stress (ultrasonic energy) transfer through installed rock bolts, a measure that is directly proportional to the degree of grout bonding of the bolt to the mine roof structure and thus the ability of the bolt to bear static stress. The rock bolt bond tester (RBBT) is a hand-held portable device that shows three ranges of bolt bond condition; i.e., one-third (Bad bond), two-thirds (marginal), or fully bonded. These are shown respectively by a red, yellow, or green light that displays for 4 s. RBBT performance was verified with 2 1/2-to 8-ft bolts installed in various types 0f mine roof structures (sands tone, shale, and boney coal-mud), and 15 now being tested by the Bureau of Mines in mines across the United States. The unit is about the size of a five-battery flashlight and contains the transducer electronics, and battery pack. The RBBT is designed for extreme ease of operation, requiring only manual contact with the bolt and signal read-out. The batteries are rechargeable and the package is designed for durability in a mine environment.

Jan 1, 1983

By John R. Rhodes

The objective of this project was to investigate the feasibility of analytical techniques potentially capable of determination of Mg, Al, Si, S, Ca and Fe in 1 to 2 mg samples of respirable coal mine dust, in a total analysis time of not more than 10 minutes per sample, using equipment capable of being truck mounted for field-laboratory operation. It was not essential that the technique be non-destructive, but the chosen technique is, and this enables the analysis to be performed directly on the 37 mm diameter membrane filter on which the respirable dust sample is normally collected. The sensitivity requirements are therefore quoted in terms of the units of measurement, µg/cm2. The detection limit (3o of the background criterion) should be 0.5 µg/cm2 or less. The precision should be 5% or better, at concentrations above which the detection limit is not the determining factor.

Jan 1, 1972

By Flávio Parreiras Marques

A microabrasão é uma técnica para produzir desgaste abrasivo em escala micrométrica. Neste trabalho estudamos uma liga fundida de cobalto com composição química próxima à da superliga comercial Stellite 6com composição eutética sendo a matriz constituída por uma solução sólida de cobalto, cromo e molibdênio que embebe uma grande quantidade carbonetos eutéticos de cromo. O objetivo deste estudo é avaliar a resistência ao desgaste bem como os micromecanismos dominantes através de ensaios de microabrasão. Foram usados três diferentes tipos de lama abrasiva, sílica, alumina e carbeto de silício com uma concentração de 0,1 g/cm3, carga de 0,3 N e uma distância deslizada de 48 metros. O menor coeficiente de desgaste foi obtido com sílica e o maior com carbeto de silício. O micromecanismo dominante foi o riscamento com riscos em toda superfície da amostra e presença de indentações apenas na matriz.

Aug 16, 2017

By R. H. Hiltz

One of the major hazards in underground coal mining is fire. The inherent hazard of fire is exaggerated by the nature of coal mining restricted areas, the highly combustible nature of coal itself, and a potential for explosive concentrations or dust and gas in the air it becomes imperative therefore to make every effort to eliminate the causes of fires, while providing the most effective means possible to control and extinguish those fires which may occur it has been demonstrated by prior work that the problem of control increases in proportion to the time necessary to institute control procedures. There are several areas of underground coal mining with obvious fire potential. Some of these, like belt heads, have reliantly undergone improvements in standby fire control devices Others, although having fire suppression systems available to them, have not received as complete a systematic study of their problems. Face machinery, particularly those without a water supply, falls in this latter category.

Jan 1, 1973