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By Joseph P. Lyden

In the Picher field, structure made openings for the circulation of the mineralizing solutions by flexing, shearing, and fracturing the sedimentary beds. This structure is used with the spatial and genetic relationship of the ore minerals, sphalerite and galena, and the gangue minerals, dolomite and jasperoid, in prospecting for ore bodies.

Jan 12, 1950

By Bruce K. Hebblewhite

This paper provides an overview of the international ?state of the art? with respect to underground coal mining methods used in seams of thickness greater than 4.5 m, through a review of a selection of high performing thick seam mining operations around the world?both Single Pass Longwall (SPL) and Longwall Top Coal Caving (LTCC). The paper discusses the recent operational experiences from these selected faces, together with the ground control issues faced, and identifies some of the major, inherent geotechnical factors that can influence the mining method selection, design criteria, and ultimate performance, from both an operational and safety perspective. It is clear that both of these methods are developing quickly? not only from an operational and equipment perspective, but also from the understanding of critical geotechnical criteria. There is an increasing role for both methods in thick seam environments, although the higher SPL faces will only be successful in the near to mid-term under benign geotechnical environments. Regardless of the method, a thorough understanding of the critical geotechnical factors is a key to successful implementation of either method.

Jan 1, 2013

By C. D. Wiseman

THE concept of alloying to increase the strength of metals originated during the bronze age. However, at the present time there is no single theory capable of explaining all of the observed strengthening effects of alloying elements on the mechanical properties. In general, it may be said that solid solutions are stronger than the pure metal and that the strengthening effect increases with increasing alloy content. Various theories for solution hardening have been proposed, the first of which was presented by Rosenhain who suggested that the alloying elements roughened the slip planes, thereby requiring a higher stress to initiate slip. Recent work by French and Hibbard2 confirmed Norbury's3 conclusion that those alloying elements which cause a greater change in lattice parameter have larger effects on hardness. However, a given change in lattice parameter produced by different alloying elements does not cause the same change in hardness. A further refinement was suggested by Dorn, Pietrokowski, and Tietz4 who considered differences in valence between the solute and solvent with the change in lattice parameter to explain the plastic properties of aluminum alloys. Allen, Schofield, and Tate5 further investigated the valency contribution to solution strengthening by testing some copper-base solid-solution alloys having constant electron densities. Tensile tests performed on these alloys gave identical stress-strain curves even though the atomic size effect, which varied by a factor of two, was neglected. The advent of dislocation theory6-8 provided a new and powerful tool capable of explaining many phenomena of plastic deformation and indicated new approaches to solution hardening. The basic con- cept of recent theories is that solution hardening is not due to stresses associated with randomly dispersed solute atoms, but rather to a nonuniform distribution of the solute. This conclusion was reached by consideration of the effective tension present on each dislocation line and the ability of a dislocation to pass an obstacle. cottrell suggested the possibility that the internal stresses due to randomly distributed solute atoms would offer essentially no resistance to the passage of dislocations. He reasoned that an edge dislocation may be considered as a rigid line discontinuity. As the dislocation moved through a crystal, the random stress fields would be equally distributed along its length. Since half of the stress fields would be acting to move the dislocation forward and the other half trying to move it back, the net effect on the dislocation would be zero. Thus the randomly distributed solute atoms would not contribute appreciably to solution strengthening. Mott and Nabarro10 considered the dislocation as a flexible, rather than a rigid, discontinuity. They obtained a simple model for a dislocation moving in a lattice having precipated particles, where the dislocation would actually bend around the obstacle until it would loop back onto itself to rejoin and then continue onward. Their work indicated that the minimum radius of curvature of the dislocation line, under the action of an external stress and in the region of an internal stress, would be such that the dislocation would be unable to pass through a matrix containing small closely spaced precipates by the looping process. The dislocations would tend to remain rather straight, approaching the condition of Cottrell's rigid dislocation. Hence, the strengthening must not be due to random solute atoms; however, it might be due to the concentration of atoms, either as clusters of like atoms or as short-range ordered regions, or to the concentration of solute atoms around dislocations. To date, four mechanisms of solution strength-

Jan 1, 1959

By Shadrack Nuamah, Erik Westman, Bright Afum, Jesse Addy

Rock fragmentation is the most critical aspect of hard rock production blasting due to its significant impact on drilling and blasting costs and the economics of subsequent loading, hauling, and crushing operations. This study analyzes current cost trends in the drill and blast operations of an anonymous open pit gold mine and proposes cost-effective drill and blast geometric parameters. The investigation focused on one operational pit with provided design parameters for two shots, shot 1 and shot 2. Existing blast parameters and two additional proposed sets of geometric parameters were evaluated using the Kuz-Ram and Chung and Katsabanis fragmentation models to estimate mean fragment sizes. The results indicated that the proposed blast parameters produced estimated mean fragment sizes within the mine’s desired range (not exceeding 45 cm). Additionally, the explosive energy was utilized efficiently per in-situ material blasted. The proposed parameters increased the estimated total volume of in-situ material fragmented by approximately 14% for both Shot 1 and Shot 2 compared to the current parameters. Furthermore, adopting the proposed blast parameters could lead to significant cost savings. The evaluated total drill and blast cost savings were approximately 11% for Shot 1 and 12% for Shot 2. These savings stem from the increased efficiency and effectiveness of the blast operations, highlighting the potential for substantial economic benefits. This study demonstrates that optimizing blast geometric parameters will allow open-pit mines to achieve desired fragmentation, utilize explosive energy more effectively, and realize considerable cost savings in drill and blast operations.

Jan 21, 2025

By W. Wan

Diesel particulate matter (DPM) emitted from diesel engines is currently considered to be a health problem in underground mines. As a result, attempts have been made to control DPM both by reducing emission rates and by managing the DPM that gets into the mine atmosphere. This paper presents a method for modeling the generation, transfer and distribution of DPM in the mining sections through the use of a convection-based computer model so that controls for emitted DPM can be evaluated. A variety of ventilation strategies and diesel deployment schemes for room-and-pillar development sections were simulated to compare their effects on average DPM concentrations at several fixed and mobile personnel locations in the section. Input data for the model was gathered from actual diesel development sections and derived from experimental study results provided by other researchers. Studied using the model were ventilation schemes using vent tubing and brattice, exhaust location strategies on the vehicles, and the direction of ventilation at the feeder-breaker location. A summary of results from this study will be presented.

Jan 1, 1994

The inquiry into the explosion at the Moura No. 2 Mine in August 1994 recommended -?Emergency procedures should be exercised at each mine on a systematic basis, the minimum requirement being on an annual basis for each mine.? (Windridge et al. 1996). In December 1996 the ?Approved Standard for the Conduct of Emergency Procedures Exercises? was published and has been subsequently revised (Queensland Department of Mines and Energy Safety and Health Division 1999). This document provided guidelines for conducting mine site emergency exercises as well as the requirement for a test of state-wide emergency response by holding a Level 1 Mine Emergency Exercise at one mine on an annual basis. From 1998 to date (January 2008) ten Level 1 Mine Emergency Exercises have been held in Queensland, Australia. This paper discusses each of the exercises conducted to date as well as the logistics, scenario preparation, planning and organising required to conduct emergency exercises at this level.

Jan 1, 2009

A two-dimensional time-dependent analysis of a overburden-coal pillar-weak floor strata interaction problem is presented as a beam model consisting of a composite roof beam resting on multiple elastic foundations (pillars) underlain by a composite rock mass representing immediate floor strata. Several different material models may be considered for the immediate floor strata. The analysis can include all openings and pillars in a panel and permits bed separations in the roof composite beam. The model has enabled identification of the relative significance of different geometric and mechanical behavior parameters which govern the system. The paper presents the theoretical background for the model as well as its application to a mine in Illinois where surface and underground geotechnical observations have been conducted over the last two years.

Jan 1, 1988

By Siyuan Zhang, Lu Lin, Yanping Bao, Wei Xiao, Chaojie Zhang

In order to decrease high aluminum consumption in Interstitial-Free (IF) steel production in a steel plant, Ruhrstahl Heraeus (RH) process data from 2428 heats were analyzed by statistical methods. The results showed that the blowing oxygen quantity and oxygen activity, before the RH and before deoxidization, have positive correlations with aluminum consumption, especially the blowing oxygen quantity. Waiting time before refining also has a positive correlation with aluminum consumption when it exceeds 7 min. On the contrary, steel temperature before RH has a significant negative correlation with aluminum con sumption, when it is between 1600 and 1630 °C. According to the statistical results, the RH refining process was optimized when the steel temperature before RH was controlled between 1630 and 1645 °C, waiting time was controlled at less than 7 min, blowing oxygen quantity was controlled to less than 100 m3, and the oxygen activity before RH was controlled between 0.050–0.075%. After optimization, the reduction of aluminum consumption was remarkable. Average aluminum consumption decreased from 1.45 to 1.17 kg/t steel.

Mar 1, 2017

By Thomas C. Patton, Eric S. Cheney

L-D gold mine is 3 miles south of Wenatchee, central Washington. Recognition of locally mappable conglomerates, sandstones, and shales within the Paleocene (?) Swauk formation led to the discovery that the known epithermal gold mineraliza¬tion is limited to a previously unknown imbricate thrust zone of unknown displace¬ment cutting the open folds o f the area. Hypabyssal intrusions also are most nu¬merous along the trace of the thrust faults. Yakima basalt of Miocene age uncon¬formably overlies the Swauk formation, thrust faults, and the intrusions. The L-D mine is in a northwesterly trending imbricate fault block of nearly vertical strata. Microscopic native gold, electrum, and naumannite occur in quartz veins and as low¬grade disseminations in the well-silicified portions of arkosic sandstones. Fault gouge on the "footwall fissure" limits ore to the hanging-wall block of the fault. Epithermal mineralization and alteration are spatially related to the nearby intrusions. Right lateral north-south faults offset the ore a maximum of 300-400 ft along any one fault. From 1949 until January 1967, when the L-D mine closed, 1,036,572 dry tons of ore valued at $14,962,305 and averaging 0.396 oz Au per ton and 0.607 oz Ag per ton were mined. Recognition of the structural control of the mineralization and altera¬tion within the Swauk formation suggests several areas within and outside of the mine that warrant further exploration. For example, the high-angle faults, imbricate thrusts, and the intrusions of this area are on strike with similar features along the major Entiat fault zone 10 miles to the northwest. The L-D gold mine (previously called Squilchuck, Wenatchee, Golden King, Gold King, and Lovitt) is located in Squilchuck Canyon about three miles south of Wenatchee, Chelan County, Wash. (Fig. 1) on the eastern edge of the Cascade Mountains. The major stratigraphic unit in the area is the nonmarine early Tertiary Swauk formation, which is predominantly com¬posed of arkosic sandstone. The lack of laterally per¬sistent units and the paucity of outcrops heretofore have precluded all but the grossest subdivision of the Swauk.' As a result, the true significance of the open folds in the Wenatchee area was not recognized, and although the geology within the mine was known, the structural setting of the mine was virtually unknown. During the present investigation, several locally map¬pable units were discovered within the Swauk which, in conjunction with mine maps, indicate an imbricate thrust zone. The epithermal gold mineralization, most of the hypabyssal intrusions, and the zones of hydrother¬mal alteration are located within or near this thrust zone. The purpose of this paper is to: (1) to describe this structural setting, rather than the detailed mine geology already presented by Lovitt and Skerl,2 and (2) to sug¬gest that from an exploration standpoint, this struc¬tural setting may be repeated in areas inside and outside of the mine area. Stratigraphy and Structure of the Swauk Formation General: The Swauk formation contains three distinct lithologies. Typical Swauk sandstone is gray on fresh surfaces, poorly sorted, weathers tan, and is cross¬bedded; it consists of 40-60% quartz, 20-40% feldspar, and up to 10% muscovite and biotite 9 The typical shale is gray to dark brown, very soft, and interbedded with silty sandstones; sharp contacts exist between the

Jan 1, 1972

By J. M. Oestreich

Supercritical water (sew) Is being tested for commercial use 1n several organic extraction systems but little work has been done on the extraction of metals from minerals. This lack of information prompted Bureau of Hines (BOM) research into the sew treatment of minerals. As a result, this research project is intended to serve mainly as a starting point for further experimentation. A simple flow-through reactor was built out of high pressure tubing and used to treat minerals with SCU at 400? C and 3500 to 7000 psi. The research produced four main conclusions: (1) carbonates of copper, iron, and lead convert to oxides; (2) most iron minerals showed alteration to oxides with some iron dissolution; (3) valuable trace elements including nickel, chromium, and others leached to some extent from sea minerals along with some calcium, iron, silicon, and sulfur; and (4) treatment of sulfides extracted elemental sulfur and resulted in several alteration reactions, though with the exception of cinnabar and the iron bearing minerals, the metals in sulfides were mainly insoluble. Surface alterations on many of the minerals show significant changes have occurred in the minerals even when only minor extractions were detected. These surface effects may be very important when used in conjunction with flotation processes since the sew treatment may selectively enhance or suppress a mineral's floatability.

Jan 1, 1989

By Chinmay Shingote, Robert Visintainer, Renjie Ke, Jaikrishnan R. Kadambi, John Furlan

Hydrocyclone separators are some of the most widely used instruments in a variety of industrial applications. Their major functions are to sort, classify and separate solid particles and liquid droplets within a multiphase flow system. Research studies employing both experimental and numerical methods recognize that the performance of a cyclone is related to its geometric dimensions as well as the inner flow pattern. Although many successes have been achieved over the past years, the majority of investigations only focused on the simplified design of cyclone geometry and on single-phase flow. Therefore, this study set out to investigate the flow field in a new-design hydrocyclone and used particle image velocimetry (PIV) to explore the complex swirling flow behavior inside the cyclone within an air core. The flow field inside the cyclone was also studied by computational fluid dynamics (CFD) simulation using a commercial CFD package. Different turbulent models were tested in this study with a moderate-size mesh, and the interface of liquid phase and air phase was predicted by the volume of fluid (VOF) model.

By P. S. Rudman

Laves phases, AB2, are considered as Izerrzisub-stitutional solutions m1hich are defined by a one-for-truo replacement scheme. Atomic-size tnisfit is considered in terms of deviations of the ratio 2V°b/V°A from unity, where v° = atomic volume. A simple elastic model has been used to calculated deviations from "Vegard&apos;s law of atomic vol-umes". Comparison has been made between calculated and observed atomic-volume deviations fov 222 Laves phases. Agreement is generally very good although there ave some few exceptions which appear to be excusable in terms of electronic changes that ore beyond the scope of the present model. We can consider the formation of a binary sub-stitutional solution A-B from an A solvent as one-for-one replacements of A atoms by B atoms. As the atomic-size ratio deviates from unity, the solution becomes thermodynamically less stable and hence more restricted because of atomic-misfit strain energy. In accordance with our previously presented conclusion1 that the atomic volume, v, is in general the most appropriate measure of atomic size, the ideal size ratio for a binary sub-stitutional solution is vg/vA = 1. The Laves phases have been described by Berry and Raynor2 in terms of various stacking sequences of hexagonal layers of B atoms for the three structures MgZn2(C14), MgCu2(C15), and MgNi2(C36). To form the Laves phase of ideal composition AB, we start with complete hexagonal layers of B atoms in the appropriate stacking sequence and we remove, according to an appropriate scheme for each structure, two out of every four B atoms and replace the two removed atoms by one A atom. We thus might expect to find that the ideal size ratio for the Laves phases is 2v/B/ VA= 1. From this point of view, then, we call Laves phases hemi-substitutional solutions since we employ one-for-two replacements. By analogy with substitutional solutions we can expect for Laves phases that as the ratio 2VB/Va deviates from unity the phase occurrence will be more restricted. Laves3 has plotted the distribution of Laves phases as a function of the radius ratio, ?A/rB, and found that, while the distribution extended from 1.05 < rA/B < 1.50, the

Jan 1, 1965

By A. L. Mowry, John T. Norton

Isothermal sections of the pseudo-ternary carbide systems TiC-VC-ZrC, TaC-VC-ZrC, and NbC-VC-ZrC have been examined. The sections contain an inverted U shaped two-phase field whose maximum extent is 77 molecular pct for Tic, 64 pct for TaC, and 51 pct for NbC. lsoparametric lines were determined which show the curvature of the single-phase field and the direction of tie lines in the two-phase field. It was not possible to show any relationship between atom size and the extent of the two-phase field. REVIOUS work&apos; on the solubility relationship of several pairs of refractory cubic monocarbides from the group Tic, ZrC, VC, NbC, and TaC has shown that, with the exception of the system VC-ZrC, they all form continuous series of solid solutions. It was demonstrated that the limited solubility in the case of VC-ZrC system was primarily a question of the size factor, the size difference between vanadium and zirconium being greater than the limiting value of about 15 pet. It is interesting to consider the results of combining these isomorphous carbides in groups of three and to determine the isothermal section of the pseudo-ternary diagram at, for instance, 2000°C, a temperature that will assure an equilibrium structure in a reasonable length of time. In the ternary systems where the three pairs form complete solid solution series, it is probable that the isothermal ternary section would be a single- phase field, although this is not necessarily the case. However, if one pair of carbides has a very limited solubility, then there must be a two-phase field of some extent, and it is the purpose of the present work to examine the extension of this field and to determine if it can be related to the nature of the third carbide. This condition is fulfilled if the VC-ZrC pair, which has only limited solubility, is combined with Tic, TaC, or NbC. The relative sizes of the metal atoms undoubtedly play a role in the extent of the single-phase field, and the values obtained from the pure carbides, assuming close-packing between metal and carbon atoms and a carbon atom diameter of 1.54A, are

Jan 1, 1952

By Mohamed Hassan, Matthias Seip, Steffen Leppla

In the east of Frankfurt am Main, Germany, a new high-rise building is planned directly next to the river Main. The high-rise building will have a height of about 75 m and will be founded on a Combined Pile-Raft Foundation (CPRF) in the tertiary marl. The new structure will be constructed next to important, sensitive traffic infrastructure. The foundation of the new high-rise building adjoins directly existing historic quay structures, which are more than 100 years old. For analysis of the stability and the serviceability of the heavily eccentric loaded foundation of the new high-rise building and the existing structures and for the investigation of the soil-structure interaction complex three dimensional, non-linear numerical simulations have been carried out. These numerical simulations take into account all geometric and material specific boundary conditions, including the history of the construction of the whole area. The paper introduces into a very complex construction project in which the investigation of the soil-structure interaction has an important role. The three-dimensional numerical simulations are explained and the results are shown.

May 1, 2022

By A. K. Ghose

The increasing application of roadheading machines in the coal industry has prompted the development of an appropriate selection methodology for such machine applications in specific locales. Accurate geological sections and comprehensive rock testing are required for all machine tunneling. Using suitable geotechnical parameters and index tests, sensitive both to excavability and standability of the strata, a classification scheme has evolved to help evaluate the rock mass vis-a-vis application of a given weight-class of roadheading machine. The classification parameters include point load index, brittleness, abrasiveness, average crack density, and ground water, which with assigned numerical ratings, lead to a quantitative global rating of the rock mass. For each rock mass class, the selection of an appropriate roadheading machine is recommended. The paper illustrates the application of the rock mass rating system and also describes simple index tests for evaluating the classification parameters for brittleness and abrasiveness. Manuscript not received in time for publication.

Jan 1, 1983

By E. S. Davenport

IT is indeed an honor and a responsibility to have been selected to present the thirty-fourth in this series of Henry Marion Howe lectures, established to perpetuate the memory of a great teacher and one of America&apos;s outstanding scientists. Previous Howe lecturers have established high standards for this annual AIME event. It has been my good fortune to have enjoyed close association with five of these former lecturers; namely, Bain, Grossmann, Johnston, Sosman, and Vilella, all of whom have been prominently identified with the research activities of the organization with which I am connected. Some years ago I had an opportunity to examine a letter written by Professor Howe in 1904. This document was particularly interesting to me since I never had the privilege of personal acquaintance with Professor Howe and do not recall even having seen him during his long and active career. In view of the fact that the letter dealt, to some extent, with matters related to the subject of today&apos;s lecture, I would like to quote briefly from it. The letter is datelined, "Bad Kissingen, June 11, 1904." The salutation reads, "Dear Bradley," which suggests that it was probably addressed to Bradley Stoughton, who, I believe, was working with Howe at Columbia University at that time. The letter reads, in part, as follows: "Austenite and Martensite. I have not examined what Osmond says in his new book. His former remarks about austenite I found very confusing, indeed unintelligible. I think we can reconcile matters well enough for the present by assuming that martensite is a transition step between austenite at one end and ferrite and cementite at the other. Above critical range for steel of 0 to 1.80 carbon, austenite is normal state; below Ar1, ferrite and cementite are normal." The letter then continues with a discussion of Osmond&apos;s ideas on metallographic nomenclature, particularly his use of the terms martensite, troostite, and sorbite, including the following pointed comment: "For common purposes it seems to me unwise to drag them in, and much simpler to confine ourselves to the end stages Austenite Ferrite plus Cementite Osmond does not really know his own mind— or does not clarify his ideas to others—as to nomenclature." Thus we see that, as far back as 1904, the transformation of austenite, and the products of that

Jan 1, 1958

The An Shan iron ore deposit is the biggest low-grade oxidised iron deposit in China. Over the past ten years, about 120 SLon verticalring-pulsating high gradient magnetic separators units have been installed in An Shan to process oxidised iron ore. This paper describes how several plants have upgraded their old technologies to new technologies with SLon magnetic separators as the key equipment for controlling tails grades, including using reverse flotation as the key technology for iron concentrate cleaning, These plants have been modernised with beneficial results at low cost.

Jan 1, 2009

By D Zielinski-Nicolson

The emergence of affordable, portable and versatile wireless devices has enabled a new frontier in mine safety equipment. Existing solutions provide methods for tracking personnel and assets in underground mines but are not designed to optimally integrate into existing and emerging systems. Mine management are often required to coordinate primarily independent emergency, personal protective equipment (PPE), tracking and collision avoidance systems from multiple vendors. These systems involve a variety of wireless technologies that require separate integration projects that discourage adopting new services and policies.

May 5, 2022

By Carle Hayward

THE effect of copper on steel has been studied by numerous investigators. Before modern testing methods had been developed, blacksmiths noted red shortness in iron, the cause for which was ascribed to the presence of copper. Numerous papers have been published on the corrosion of steels containing various amounts of copper, and a few writers have discussed the effect of copper on the mechanical properties of steel. The purpose of the investigation described in the following paper was to obtain additional data on the mechanical properties of medium-carbon steel containing small quantities of copper. Among those who have published results of mechanical tests on copper steels are Ball,1 who states that copper increases the tensile strength and &apos;hardness but lowers the elongation. Stead2 states that copper steels closely resemble nickel steels containing equivalent percentages of nickel,, as regards tensile strength, resistance to shock, corrosion and hardness. Wigham 5 found that copper in small amounts had no injurious effect on steel. Breuil4 found that with 1 per cent. carbon, copper lessened the brittleness of steel and in low-carbon steel it increased the tensile strength and lowered the ductility slightly. H. H. Campbell 5 states that copper up to 0.25 per cent. slightly raises the elastic limit, elongation and reduction of area.

Jan 1, 1918

This surveillance report summarizes data on work-related fatal and nonfatal injuries, illnesses, and hazardous exposures in the mining industry for the 10-year period 1986-1995. The term ?surveillance,? as used in public health, may be new to many readers of this report. With regard to occupational safety and health, the goal of surveillance is to describe the occurrence of work-related injuries, illnesses, and known hazardous exposures; to identify new hazards that may occur due to the introduction of new technology or other factors; and to assess the effects of preventive measures designed to improve worker safety and health. Surveillance provides an overall picture, which can be used to focus resources on areas most in need of prevention programs or further research. Surveillance generally requires the use of multiple sources of data, all of which have their own strengths and limitations. Surveillance in the U.S. mining industry is complicated by the fact that U.S. national data systems that provide information on mining are based on two different definitions of the mining industry. One is established by the Mine Safety and Health Administration (MSHA), the other by the Standard Industrial Classification (SIC) System [Office of Management and Budget 1987] and the 1980 U.S. Bureau of the Census (BOC) Classification System [U.S. Bureau of the Census 1982].

Jan 1, 2000