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By B Mohanty

Several parameters such as, Energy, Strength, Brisance, Impulse, and Bubble Energy, are in common use in the explosives industry today to rate commercial explosives in terms of blasting performance. However, this multiplicity of terms, their frequent interchange and their purported one-to-one correlation with expected performance have given rise to a considerable amount of confusion, and have often resulted in unrealistic rating of explosives. In this paper, various theoretical and experimental methods of estimating energy and performance of explosives are discussed and their relative merits examined. These methods include, Computer Code Calculations, Cylinder Test, Trauzl Test, Ballistic Mortar Test, Underwater Test and Model-scale blasting. It is shown, in the light of actual blasting process, that such measures cannot be considered accurate indicators of expected blasting performance as the properties of rock to be blasted are either totally ignored or only partially accounted for in these methods. It is also shown that no single technique alone among those currently employed by the explosives industry can lead to realistic rating of explosives in terms of expected blast results. The need for the adoption of a two-tier rating system, one based on chemical potential "energy", and the other based on blasting "performance" is proposed, and specific approaches to achieve this objective are outlined.

Jan 1, 1981

By J. Beddoes

The various microstructural factors that influence the creep resistance of y-titanium aluminides are presented and discussed. Titanium aluminides have potential for a variety of intermediate temperature applications in both gas turbine and reciprocating engines. While it is well established that the 'fully lamellar' titanium aluminide microstructure offers superior creep properties, the particular influence of lamellar morphology, third phase precipitation, and grain boundary structure in controlling both the primary and tertiary creep behaviour is presented. The results are primarily based on tensile creep experiments undertaken using several titanium aluminide intermetallic compositions processed via powder metallurgical techniques, investment casting and Bridgman directional solidification. The results indicate that lamellar structure and precipitate formation have a major impact on primary creep, while microstructural degradation through both lamellar and precipitate coarsening influence on the onset of tertiary creep leading to fracture. The results are used to design a creep resistant microstructure produced by directional solidification and the effectiveness of this designed microstructure is demonstrated through 10,000 hour creep tests.

Jan 1, 2004

By Alan Galley

CMIC Mandate CIM Annual Meeting, Toronto, May 6, 2013 To increase mining research, innovation and commercialization efforts in order to strengthen Canada?s pre-eminent role as a global leader in mineral exploration, mining and knowledge-based services and technologies. To increase the supply of highly qualified graduates from mining and earth sciences faculties to meet the significant demand today and into the future of industry, governments and academia. The CMIC initiative is intended to develop long term research strategies that extend five or greater years. Such a research plan will underpin fundamental research and innovation and the training of HQP

May 1, 2013

By W. E. C. Coxe

MANY of you who are interested in the manufacture of iron and steel, have no doubt heard of the "Wheeler process for combining iron and steel." Mr. Wheeler has formed a company, styled the "Combination Trust Company," whose business is to grant licenses for the use of this patent process in producing what he calls "iron-clad steel." It has been proposed to apply it in the manufacture of car or wagon axles, also to shafting, having steel cores or centres covered with iron; to tubes of steel with an inner and outer skin of iron ; to structural purposes, such as girders and beams; bridge and tie-bolts, where the strength of the iron and the rigidity of the steel would be desirable. In answer to a request from Mr. Wheeler, permission was accorded him to make some experiments at the rolling mill of the Philadelphia and Reading Coal and Iron Company, at Reading, Pennsylvania, with a view to manufacturing some steel-headed rails. In making this kind of a rail two difficulties are encountered. If the iron is brought to the requisite heat to weld properly, the steel is likely to be burned ; if the steel is cared for, to prevent burning, the several layers of iron are not brought up to the proper welding heat. Mr. Wheeler claimed that the steel slab covered with iron which be furnished for the head of the rail could not be injured by any heat to which it might be subjected in the ordinary course of heating the rail-pile. He claimed, also, that by this method the porosity, which he thought was characteristic of all solid rails of Bessemer steel, would be overcome. Four steel slabs were furnished for this experiment, being Bessemer steel of .61 carbon, made at the Edgar Thomson Steel Works, and covered with iron in one of the Pittsburgh mills. The slabs were in section seven inches wide by three inches thick, and the iron covering was one-eighth to three-sixteenths inch thick. Each slab was placed on a pile of iron made up in the ordinary way for a rail fifty-six pounds per yard and thirty feet long. The heating was under the personal direction of Mr. Wheeler, and

Jan 1, 1879

AustraliaÆs success as a mineral producer and exporter rests heavily on its technological competence. That competence is based not just on adopting internationally-developed technology but also on ground breaking research conducted at Australian research institutions, many of which have global reputations. A number of forces are now operating to speed the introduction of advanced technology to mining and processing operations around the globe and this will create pressure on the Australian industryÆs ability to retain its competitive edge. Examining the foundations of that national research base and the associated culture of innovation may provide some guide to the dynamics that will be required to maintain technical competitiveness in the future.

Jan 1, 2008

By Roberto Pimentel de Souza, Helder Zenóbio

VRD started producing pellets in 1969 with one 2-million-t straight grate plant. In the beginning of April 1973, the second unit came on stream with an additional capacity of 3 million t/a of pellets. In January 1977, the third unit started, bringing the annual capacity to 8 million t/a. In the coming year (1978-79), three more units, 3 million t each, are expected to begin production. CVRD's experience with different binders and additives is described. Over the years several kinds of pellets have been produced to satisfy market requirements. General quality information is given for each.

Jan 1, 1981

By H. G. Denkhaus

Please allow me the temerity to reply to your reply to my contribution as follows: A fracture is brittle if plastic deformation is absent or, conversely a fracture is ductile if plastic deformation is present. Consequently, brittleness is specified by the degree of plastic deformation at fracture. This is the generally accepted definition. If other material properties (e.g. the quorient or the product of the uniaxial compressive and tensile strengths) under certain conditions are influenced by brittleness, or brittleness by them, these should not be called brittleness. If the one or the other author does that, he simply uses imprecise language. Even your remark, that ?Inyang and Pitt (1990) stated that the ratio of the compressive strength (sc/st) is directly proportional to brittleness?, confirms that the two quantities are not considered the same. For example:? The well known definition that a material is linear?elastic if the strain is directly proportional to the stress?does not mean that stress (measured in MPa) and strain (measured in %) are the same thing.

Jan 1, 2003

By Tamara Nestorovic, Luan T. Nguyen

"With the aim to mitigate excavation risks and reduce the costs caused by tunnel boring machine (TBM) stoppage when tunneling under uncertain soil conditions, prediction ahead of the tunnel face has become an increasing interest in the tunneling community. Our research topic is concerned with developing effective concepts for nondestructive identification of geological anomalies ahead of the tunnel face by waveform inversion of reflected tunnel seismic waves. The authors demonstrate that this new technique is promising in providing tunnel engineers with an accurate image of the geological situation that the TBM is going to encounter thanks to the waveforms’ rich information about the geological structure that affects propagation, reflection/refraction and mode conversion behavior of the elastic waves. By setting up a 2-dimensional numerical model for simulation of tunnel seismic wave propagation influenced by a dip layer change ahead of the tunnel face, the authors show that the waveform misfit to be minimized by the inversion process is highly multimodal and therefore propose a hybrid stochastic optimization method that can quickly and robustly converge to the global minimum. DEVELOPMENTS IN TUNNEL ADVANCE EXPLORATION Conventional site investigation by drilling boreholes helps to draw a general image of geological structures along the borehole axes but that image is likely to misrepresent the detailed geological structure due to limited sampled locations. Due to high costs and restricted boring space which deep tunneling and tunneling under urban areas encounter, many industrial and academic research groups have had great interest in developing nondestructive ahead of the tunnel face prediction systems. That means only excitation sources and receiving sensors, which are usually placed on the ground surface or on the side walls or on the cutter head of the TBM, are used for acquisition of the measurement data. The recorded signals in the form of seismic or electromagnetic/ electrical waves, which travel through the geological structure or are reflected back from it, hold the signature of the geological structure of concern, such as geological layer changes, fault zones, erratic rocks, boulders, construction remnants, etc., and therefore can be used to reconstruct the spatial and material properties of those hidden geological structures. Most common nondestructive ahead-of-tunnel investigation systems to date are based on interpretation of reflected elastic/ acoustic waves (seismic waves) and analysis of electromagnetic/ electrical resistivity signals (Mooney et al. 2012). However, due to insufficient penetration depth and spread of signals generated by radar and geoelectric sources, the use of seismic waves for ahead of the tunnel face prediction (tunnel reconnaissance) is more preferable (Kneib et al. 2000; Bohlen et al. 2007)."

Jan 1, 2016

By E. E. De Beer

This paper describes a method for the determination of the settlement of an individual H-bearing pile, based on the results of CPT-tests. As implied by the nature of the problem, no analysis performed on one pile can be regarded as generally valid for a whole piling foundation project because, even on one site, the pile behaviour varies from one pile to another. Consequently, no precise mathematical analysis has been established; the proposed procedure represents a simple model for the determination of the probable settlement behaviour of an H-pile under a compressive load. Prior to the settlement computations, the rupture load and the resistance distribution along the pile have to be determined. Since the method for the determination of the H-pile bearing capacity from the results of CPT tests has been described elsewhere (de Beer, 1971, 72; de Beer et al., 1982; Arbed, 1985), no details will be given in this paper. The proposed method is valid for both uniform and non-uniform H-piles. The computed results have been satisfactorely compared to the static loading tests performed on different types of piles in clayey and sandy soils during an ECSC research program on H-bearing piles (1983-1987).

Jan 1, 1987

The history of surface mining is essentially that of mining coal, copper, and iron ores and the non- metallic minerals, i.e. clays, gypsum, phosphate rock, sand, gravel and stone. The accompanying table comparing world production with that of the U. S. indicates that two thirds of the 8.8 billion tons of ores mined throughout the world come from surface operation. Assuming that the stripping ratio for surface mining in the U. S. applies equally to world production, then over 21 billion tons of waste, or a total of nearly 27 billion short tons of material are mined annually in the world by surface methods. Several factors are significant indicators of economic and technologic trends in surface mining. Among these are increasing production, a shift in emphasis from underground to surface mining, a decline in the grade and quality of some crude materials and, with few exceptions, an increase in the productivity of labor.

Jan 10, 1967

By I. W. Wark

AN attempt has been made to compare the influences of the two most widely used depressants-alkalis and sodium cyanide-and the most widely used activator-copper sulfate-on the air-mineral contact induced by five sulfur-bearing compounds: (1) sodium di-ethyl dithio-phosphate (sodium Aerofloat); (2) potassium ethyl xanthate; (3) sodium di-ethyl dithiocarbamate; (4) potassium iso-amyl xanthate; (5) potassium di-n-amyl dithiocarbamate. Three different organic types are included in this group and for two of these types a higher and a lower homologue have been tested. The study of potassium ethyl xanthate, the preliminary results of which have been described,1 was continued until there had been obtained a comprehensive account of the influence of variations in pH value and in the concentrations of xanthate, sodium cyanide and copper sulfate on the adsorption of this xanthate by galena, sphalerite, pyrite and chalcopyrite. With concentrations of copper sulfate and collector that the work with ethyl xanthate indicated would give the most illuminating results, the other four collectors were tested in a less exhaustive way. The same general principles determine the influence of alkalis, cyanide and copper sulfate, no matter to which type the collector belongs, but there is a gradation in the quantitative measure of such influence. In the list above, the five collectors are cited in the order of their capacity to withstand the depressants, sodium Aerofloat being the least resistant, potassium di-n-amyl dithiocarbamate the most resistant. This order coincides substantially with that of the solubilities of the heavy metal salts formed by double decomposition with the collectors, those formed from sodium Aerofloat being most soluble. There is little difference between the third and fourth members of the series, and under certain conditions their positions are reversed.

Jan 1, 1934

By C. M. Mason

Mechanical mining produces large quantities of very fine coal dust called float dust. The associated increase in hazard requires a reexamination of the Bureau of Mines method of evaluating the incendivity of explosives in coal dust-gas-air mixtures. A technique recently developed by Bureau of Mines laboratories for evaluating the incendivity of explosives in coal dust-air mixtures was applied, with modifications, to coal dust-air-natural gas mixtures. A series of permissible explosives were evaluated by this modified technique. Results indicate that the modified technique could be the basis of a more discriminatory procedure than that presently in use.

Jan 1, 1968

Mining companies around the globe have long struggled with the need to ensure that earth moving equipment is designed to be operated and maintained under all site conditions without causing harm to people. Incident and accident data from a range of sources clearly identify mining equipment related issues as major causal factors. One Australian source, the NSW Department of Primary Industries? International Mining Fatality Database Project Report (2008) noted that ?Approximately 77% of mining accidents resulting in a fatality have? involved equipment?. The largest number of fatalities were associated with trucks; the next with LHDs. Many of the technical advances in equipment design over the past few decades have not been matched by advances in the human factors design of mining equipment, resulting in a ?design vacuum? that must be filled prior to commissioning new equipment. This ?design vacuum? is generally filled by local dealers. They retrofit equipment according to customer requirements to mitigate risks that have not been designed out by the Original Equipment Manufacturer (OEM). Mining companies have been frustrated by lost time and additional costs associated with this need to retrofit ex-factory designs. Some companies have attempted to address the problem by negotiating company or site-wide ?solutions? to equipment designs, but this has not simplified or clarified the issue from the point of view of the equipment manufacturers. A number of mining companies operating in Australia first discussed the concept of a joint customer approach to improve the Human Factors design of earth moving equipment at the factory level in 2004. They agreed that a new approach to engaging with OEMs was needed; one that would define the ?Problem?, in other words, the basis of the risks, rather than dictate the ?Solution?. The Earth Moving Equipment Safety Round Table (EMESRT) was formally established in 2006 by six global mining companies to establish a process of engagement between Original Equipment Manufacturers (OEMs) and mining customers.

May 1, 2009

By Joe W. Siefke

The world-class Kramer sodium borate deposit is being developed by modern open pit operations near Boron, California. The deposit is a bedded, lenticular sedimentary sequence of borax and kernite crystals together with claystone. The borates dip south into a structural basin-bounding fault and were formed in the bottom muds of a permanent shallow lake. The lake was fed boron and sodium-rich solutions from a thermal spring source of volcanic origin. In addition to deposit geology, present day geotechnical concerns such as groundwater and slope stability will be discussed.

Jan 1, 1995

By Ellie Condolios

Hydraulic hoisting offers a number ~f attractive features over conventional hoisting methods: small shaft space requirements; great flexibility of layout, including pick-up or delivery of the material at points distant from the mine shaft; low investment and operating costs. However, limited practical experience with this type of hoisting dictates that careful design and, frequently, extensive testing be done by competent engineers before large-scale installations are built. This paper covers the following: basic laws and design criteria for hydraulic hoisting installations; a description of a coal hoisting installation which has been in industrial operation since 1960, with a vertical lift of 600 feet and an annual capacity of 500,000 tons of -3 ~-in. coal; and a tentative appraisal of the process, including cost estimates. THE transportation of solids in water flowing through a pipe-line has, for a number of years, been common practice in dredging, public

Jan 1, 1963

By Ronald M. Lewis

Quadratic functions, Q(hkl), are given to six places in increments of 0.01° for 2? from 00 to 90° for FeKa and from 25° to 180° for FeKa1. The wavelengths used for Fe in the computation are those agreed upon by the Editorial Commission of the International Tables for X-ray Crystallography (1950): FeKa1 1.93597 A.; Feka2 1.93991 A. INTRODUCTION At the Federal Bureau of Mines laboratory, Norris, Tenn. X-ray diffraction crystallography using tubes with iron targets revealed a need for a handy reference for the quadratic functions of iron radiation. The tables presented here were prepared to satisfy that need. The quadratic form Q(hkl) may be expressed in terms of the Bragg diffraction angle 2? and of the wavelength ? as

Jan 1, 1961

By Arthur M. Langer

Since the promulgation of the first Federal Asbestos Standard by the Occupational Safety and Health Administration in 1972, other federal agencies have modified the standard to better carry on their own unique missions. The instruments used to identify and measure asbestos, the sampling protocol, and the criteria used to define asbestos, have been modified to some degree. The Mine Safety and Health Administration regulates and controls asbestos dust in the mining and mineral commodity industries. However, crushed stone and processed ores contain mineral fragments that are frequently difficult to distinguish from asbestos. Mineral nomenclature, instruments for particle analysis, and sampling strategy must be accommodated to some degree to make asbestos control workable and meaningful. Precedent in other agencies has made consideration of these changes possible. Newly identified amphibole asbestos minerals have further complicated the agency?s regulatory charge. Changes in its Asbestos Standard are now being considered. Crushed taconite ore in the Eastern Mesabi highlights many of these issues. ©2008 Published by Elsevier Inc. Keywords: Amosite; Grunerite asbestos; Crocidolite; Riebeckite asbestos; Tremolite asbestos; Actinolite asbestos; Winchite asbestos; Richterite asbestos; Arfvedsonite asbestos; Fluor-edenite asbestos; Asbestos defects; Cleavage fragment; Mineral habit; Mesabi amphiboles

Jan 1, 2008

By W. R. Wrzensinski

This report presents the findings from a l-yr Bureau of Mines program in which sulfur concrete reinforcing materials were tested and evaluated to determine their resistance to corrosion. It also summarizes the permeation characteristics of sulfur concrete and the exemplary performance of precast, reinforced sulfur concrete structures in various industrial environments. The Bureau is furthering the development of sulfur concrete technology as part of a larger effort to find uses for the Nation's plentiful sulfur resources in construction materials. Sulfur concrete is a corrosion-resistant material that can be used in acid and salt environ-ments where conventional materials fail. Penetration of corrosion-inducing agents is minimized because of the low permeation characteristics of sulfur concrete.

Jan 1, 1988

By A. A. Bradley, K. H. Stanton, P. J. D. Lloyd

A theory for the dynamic balancing of centrifugal mills is presented that takes account of the mass and shape of the charge in a gyrated grinding tube and the way in which the charge lags behind the centrifugal force vector. predicts that a corresponding lag in the angular position of the counterweight centres of mass is necessary, and that the fractional filling should be increased if the ratio of gyration diameter to tube diameter is decreased. A worked example is given for a I MW centrifugal mill that was balanced adequately by the methods described.

Jan 1, 1983

By M. K. Mohanty

One of the main objectives of this study was to evaluate a fine-coal cleaning circuit using an enhanced gravity separator specifically for a high sulfur coal application. The evaluation not only included testing of individual unit operations used for fine-coal classification, cleaning and dewatering, but also included testing of the complete circuit simultaneously. At a scale of nearly 2 t/h, two alternative circuits were evaluated to clean a minus 0.6-mm coal stream utilizing a 150-mm-diameter classifying cyclone, a linear screen having a projected surface area of 0.5 m2, an enhanced gravity separator having a bowl diameter of 250 mm and a screen-bowl centrifuge having a bowl diameter of 500 mm. The cleaning and dewatering components of both circuits were the same; however, one circuit used a classifying cyclone whereas the other used a linear screen as the classification device. An industrial size coal spiral was used to clean the 2- x 0.6-mm coal size fraction for each circuit to estimate the performance of a complete fine-coal circuit cleaning a minus 2-mm particle size coal stream. The ?linear screen + enhanced gravity separator + screen-bowl circuit? provided superior sulfur and ash-cleaning performance to the alternative circuit that used a classifying cyclone in place of the linear screen. Based on these test data, it was estimated that the use of the recommended circuit to treat 50 t/h of minus 2-mm size coal having feed ash and sulfur contents of 33.9% and 3.28%, respectively, may produce nearly 28.3 t/h of clean coal with product ash and sulfur contents of 9.15% and 1.61%, respectively.

Jan 1, 2008