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By T. A. Wilson, S. L. Hoyt

The plastic deformation of slender single crystals of zinc has been described in some detail in the paper by Mark, Polanyi and Schmid,' which has become a classic, and also by one of the present authors in a somewhat shorter account. 2 The study of single-crystal zinc is termed classical because zinc single crystals offer, perhaps, the best material yet available for the study of atomic behavior during deformation and the effect known as "strengthening" in metals. A considerable amount of additional work has also been done on single-crystal zinc, but as it is not closely related to the present paper it will not be considered. Throughout all the former work, the mechanism of plastic deformation first described by Mark, Polanyi and Schmid has been assumed to hold. This may be said to offer the strongest confirmation of its correctness. Even so, the picture of the process has never been as completely portrayed as is desirable. The first object of the present paper is to describe work that has been done in this field, and which is even yet being carried on, in the hope that a more complete picture may be obtained. Mathewson and Phillips3 have recently described a new mechanism of the deformation of zinc based on their study of large rectangular crystals. One of their conclusions was that deformation produced twinning with a rotation of some of the basal planes into positions 94" removed from their original position; a position almost the same as that of the prismatic planes before twinning. A second conclusion was that fracture occurred along these basal planes in their new position, and, therefore that fractures previously regarded as prismatic were in reality basal. Such findings are of great significance and they raise a question as to the generality of such behavior. Professor Mathewson's opinion is that even the slender cylindrical single crystals behave in the same manner as his large rectangular crystals when strained by simple tension.

By G. L. Mowrey

One critical element of the US Bureau of Mimes computer- assisted mining research program is the development of a reliable coal interface detection (CID) system. Several promising CID concepts currently being investigated by the Bureau include natural gamma radiation (NGR), vibration and passive infrared. To help establish which CID sensor technologies need to be developed for a given seam, coal and adjacent rock samples (immediate roof and floor) are being collected from selected major coal seams in the US and are being analyzed in terms of NGR and other geophysical measurements. This paper provides a brief overview of the Bureau's work in these CID areas.

Jan 1, 1992

By M. Guarascio

Microseismic monitoring of mining areas is a developing technique, described here for the Belvedere Spinello Mine, southern Italy, where dissolution cavities in the mining area have proved problematic. The preliminary condition for locating seismic impulses has been found to be a reliable seismic ground model. Ground signals are continuously recorded by means of data from piezometric wells, for sinkhole data, and linked gephones, for microseismic data. A computer system has been implemented to collect, analyse and interpret the incoming signals consequently, identification and classification of hypocentres of activity is facilitated, with advantages in terms of safety, preventing harmful side-effects, including rock bursts, and for environmental conservation.

Jan 1, 1987

By Bhavani Kedika, Venkatagiri Noole, Krishna Thotla, Krishna Reddy Chepyala

Cationic lipids are attractive candidates for transgene delivery and expression and are safer alternatives to viral delivery vehicles. Here, we report the design, synthesis, characterization and transgene expression efficacies of a series of chrysin derived cationic lipids. A series of ten lipids of chrysin was synthesized by treating the 7-hydroxy group with dibromoalkane and further substitution of the bromo derivative with alkyl amines. The synthesized lipids were characterized spectroscopically. Parallel screening of the synthesized lipids for in vitro plasmid delivery expressing luciferase led to identification of several leads that demonstrated higher transgene expression when compared to the standard. Transgene expression efficacy was dependent on the chain length of the lipid. The influence of the various physicochemical properties on transgene expression efficacies was investigated. This study indicates that lipids derived from chrysin results in high levels of transgene expression and may be attractive for gene therapy applications.

Mar 1, 2017

By L. Giraldo, S. Cotten

"INTRODUCTION The vision for a “Mine Escape Vehicle” (MEV) is to provide capabilities to better enable underground travel to allow miners to escape to safety in the event of a major mine emergency such as a fire or explosion. Enhanced transportation and survival capability such as a MEV may have minimized or eliminated the loss of life associated with several of the mine disasters that occurred in 2006, which together resulted in the deaths of 19 miners. Although the most desirable response in an emergency is for the miners exit the mine, if escape proved to be impossible, the miners could use the vehicle to proceed to an underground point of refuge to await rescue. Under a NIOSH contract issued in April 2008, Raytheon developed a conceptual vehicle design including (1) the capacity to provide life support functions for a number of miners, (2) operate in a reduced oxygen atmosphere with little or no visibility, and (3) travel at speeds faster than miners could walk out of the mine. The proposed MEV concept envisioned modification of a personnel carrier (a.k.a. a “mantrip”) that would be used every day during normal mine operations, not a specialized vehicle reserved only for or dedicated solely to escape. The MEV concept also included escape aids that are detachable from the vehicle in the event that the vehicle must be abandoned on the way out of the mine and the dismounted miners had to proceed on foot. To advance MEV development, NIOSH awarded a second contract in 2010 to Raytheon to build, test, and evaluate the performance of a proof-of-concept MEV that culminated in a 7-month performance evaluation of vehicle in an Eastern Kentucky coal mine (Figure 1). User feedback and lessons learned from the proof-of-concept vehicle evaluation provided support for the general MEV approach, guidance related to the practicality of MEV capabilities, and indication of specific technology shortcomings for this application."

Jan 1, 2015

By A. J. Richins, M. G. Nelson, R. Dunne

From the inception of flotation in the late 1800s, coarse particle recovery has been a challenge to practitioners. By the early 1900s, flotation processes included oil flotation, skin flotation, agglomeration flotation, and froth flotation, and for each there was a proliferation of flotation equipment. Ensuring good coarse particle recovery included desliming of the feed and proper conditioning were required. Froth flotation was at first used mainly to treat finer materials from grinding circuits. The maximum size for coarse particles was from 3.18 to 4.78 mm. In froth flotation, large particles with high specific gravity tend not to be recovered. Coal and minerals of low specific gravity and flaky minerals such as graphite, mica, and talc can be floated in larger sizes. In the early 1960s, the phosphate industry began using column cells to recover coarse particle by froth flotation, but early columns suffered from poor bubble generation and sanding at the flat base of the column. Recently, improved coarse particle recovery has been the object of new cell designs—the Eriez HydroFloat™, the Jord NovaCell™, the FLS coarseAir™ cell, and the Cidra P29 integrated system. The paper will follow the development of coarse particle flotation with a focus on the development, laboratory assessment, and operation of the new flotation equipment and technology designed to recover coarse particles.

Feb 22, 2026

By Joseph A. DeCarlo

This information circular presents data for 1960 on individual coke plants in the United States. All oven-coke plants in existence, whether active or idle at the close of the year, are listed in this report. With two exceptions, only beehive plants on which reports were submitted to the Bureau of Mines are included. Although the Bureau was unable to obtain reports from these two active plants in 1960, the number of ovens and annual coke capacity are estimates, based on previous reports filed with the Bureau of Mines. Accordingly, there were 73 oven-coke plants in existence at the end of 1960 of which 70 were active. Reports were received on 44 beehive plants of which only 13 were in operation at year end. Oven-coke plants are listed alphabetically by States in table 1 which shows the name and address of the company, location of plant, classification or type of ownership, number and type of ovens, annual coke capacity, and coal-chemical materials produced. The terms "furnace" and "merchant" plants used in this and all other reports of the Bureau of Mines designate the type of ownership. Furnace plants are those owned by iron and steel companies whose main business is production of coke for use in their own blast furnaces. Merchant plants are those associated with chemical companies, gas utilities, as well as those that produce for sale on the open market metallurgical, industrial, and residential-heating grades of coke and coal-chemical materials. The annual coke capacity shown for each plant in this table is based on the minimum coking time necessary to produce coke with qualities suitable for its intended use. Therefore, the annual capacity of a plant may change from year to year, depending on age and condition of ovens, the character and quality of coal carbonized, the grade of coke required, and other factors. For example, annual coke capacity of a coke plant primarily making foundry coke with longer coking cycles would be lower than one making blast-furnace coke. Also some ovens must be operated at slightly lower than normal flue temperature because of the condition of the refractories and maximum capacity would be somewhat lower than designed capacity. For this reason, the capacity reported to the Bureau of Mines may differ from the designed or rated capacity estimated by the coke-oven builders at the time of construction. For example, if the generally accepted standard coking rate of one inch per hour were used on all ovens to calculate total annual capacity, it would have been 80.4 million tons or 2 percent higher than the capacity reported to the Bureau. Because of the factors mentioned above, the annual coke capacity shown in this table is believed to be a reliable measure of the practical operating capacity of the industry.

Jan 1, 1961

By Jack L. Henry

The Bureau of Mines conducted seven pioneering experiments in a 12-inch-diameter Kroll reduction reactor to examine the feasibility of coreducing the chlorides of Ti, AI, and V to produce a homogeneous titanium alloy sponge. The coreduction studies proceeded in a normal manner, and the yields of sponge were comparable with those of pure titanium sponge made in the same reactor. Vanadium concentration was very uniform throughout the sponge cake when VC14 in solution in TiCl4 was fed into the molten magnesium. More difficulty was encountered in feeding solid VCl2 and AIC13. Vanadium and aluminum concentration in the sponge was not uniform, and mechanical difficulties were experienced with the small-scale screw feeder. Although the sponge varied in composition from region to region, the ingots prepared from it were uniform in composition.

Jan 1, 1974

By Robert C. Johnson

Single crystal whiskers of ZrO2 and TiO2 were grown by solution and crystallization of these oxides in molten baths. Mixtures of Na2B407 and LiC1 were the most suitable growth media for zirconia. Sodium borate alone and Na2CO3 plus SiO2 were best suited for titania. The solubilities of zirconia and titania in molten sodium borate were determined, Whether zirconia whiskers were dendritic or nondendritic depended on the temperature used. The best single crystal whiskers were grown below 1,100° C. Titania whiskers always grew as single crystals. The tensile strengths of zirconia and titania whiskers were about 15,000 psi and 50,000 psi, respectively. Modulus of rupture was about 49,000 psi for zirconia whiskers and 75,000 psi for titania whiskers. Chemical analyses showed the zirconia and titania whiskers to be pure. The zirconia and titania whiskers were shown by X-ray analysis to be, respectively, baddeleyite and rutile.

Jan 1, 1965

By Carlos Martins de Oliveira

The trucking industry is constantly seeking improvement and cost reduction of their vehicles, studying new lighter and robust materials to meet the needs of its customers. The objective of this work is to study the application of DCPD Telene, PU. R. RIM and PP-TD 20 materials in aesthetic components of trucks: bumper, calender, upper and lower bracket and side air deflector. A multifunctional work team was created to work in such parts of IVECO trucks. The work began with an analysis of possible improvements to the current parts and followed the subsequent phases: definition of new materials, virtual modeling, new tools, and durability test in vehicles. It could then be verified that the proposed DCPD Telene, PUR. RIM and PP-TD 20 materials showed greater strength, better painting surface, and reduced weight and cost in parts.

Aug 8, 2018

By Jerry E. Olson

In 1988, at the request of the Bureau of Land Management, the U.S. Bureau of Mines studied additional areas, encompassing 11,303 acres, on the east and west sides of the 20,727-acre Badlands study area (Olson, 1987) in order to evaluate their identified mineral resources. The Badlands study area additions are located in Crook and Deschutes Counties, OR, about 10 and 18 miles east of Bend, OR. No mineral resources were identified. The additional areas studied are underlain by Tertiary-and Quaternary-age basalt flows which are largely covered by a veneer of sand and silt. No mines, prospects, mining claims or mineralized areas occur within or near the Badlands study area additions. Slab lava of marketable grade and quantity was not found in either area. None of the study area is of current interest for geothermal resources, but the eastern study area addition has been leased (1984) for oil and gas.

Jan 1, 1989

By C. L. Kosmoski, B. M. Eiter, B. P. Connor

"In the recent past, the mining industry has witnessed a substantial increase in the numbers of fatalities occurring at metal and nonmetal mine sites, but it is unclear why this is occurring. One possible explanation is that workers struggle with identifying worksite hazards and accurately assessing the associated risk. The purpose of this research was to explore this possibility within the mining industry and to more fully understand stone, sand and gravel (SSG) mine workers’ thoughts, understandings and perceptions of worksite hazards and risks. Eight mine workers were interviewed and asked to identify common hazards they come across when doing their jobs and to then discuss their perceptions of the risks associated with those identified hazards. The results of this exploratory study indicate the importance of workers’ jobrelated experience as it applies to hazard identification and risk perception, particularly their knowledge of or familiarity with a task, whether or not they had personal control over that task, and the frequency with which they perform that task. IntroductionAccording to the U.S. Mine Safety and Health Administration (MSHA, 2015a), 37 mine workers were fatally injured in accidents at metal and nonmetal mine sites between October 2013 and January 2015, following a record low of 16 in 2012 and in 2011. In 2014 alone, 29 mine workers were fatally injured at a metal or nonmetal mine site, and 52 percent of these fatalities occurred at a surface stone, sand or gravel (SSG) mine. In January 2015, Joseph A. Main, Assistant Secretary of Labor for Mine Safety and Health wrote to stakeholders in the metal and nonmetal mining community and identified several areas where improvement was necessary to promote the health and safety of mine workers. One area identified was an increased focus on “daily and effective workplace exams to find and fix hazards” (MSHA, 2015b).Hazard detection is challenging in the mining industry, despite the existence of regulation. Mining is a major undertaking involving the use of complex heavy machinery, equipment and processes as well as numerous and diverse worker activities that take place in a dynamic, challenging environment (Scharf et al., 2001). In other industries that are similarly dynamic and unpredictable, such as the construction industry, a large proportion of hazards go undetected (Carter and Smith, 2006). It is critical that miners are able to both recognize worksite hazards and accurately assess the risk associated with the hazards, because their health and safety depend on their deciding whether and how to remove hazards and mitigate risks."

Nov 1, 2016

By D FitzGerald

A critical component of any new tunnel design in a complex geological setting is the development of an integrated three-dimensional (3D) geology model with a full set of geotechnical properties of the rocks present. A novel means of predicting the geology based upon sparse observations of structural geology at the surface and from drill holes has been developed and used in several major tunnel studies in Europe.An example of this is the Lyons-Turin twin rail tunnel which is still in a development phase. This tunnel has been in planning and development for over 15 years already. An important aspect of this work is to characterise geological uncertainty along various possible tunnel paths as an input into early design optimisations for time, cost and risk avoidance strategies. Once the tunnel works commence and more detailed geological data is collected by daily mapping, progressive refi nement of the geological model is desirable; geological conditions still to be encountered can be more accurately predicted. Faults and their offsets, dykes, geological unconformities, folding, as well as standard sedimentary processes are all correctly modelled in the software. It is important to allow for seamless interchange of geological models at various scales with CAD workflows so that sufficient detail can be readily accessed at the required scale. Also, the proposed tunnel in its correct geometry can become a ‘section’ in its own right. Progressive detailed local geology models in the vicinity of the advancing head are created from the regional scale work by cutting and pasting a starting model, then adding all the extra detail for the required engineering geology work.For all rocks, most standard geotechnical quantities such as sonic velocities, Young’s modulus and Poisson’s ratio are handled. These and any other phenomena from borehole observations can have variograms calculated and stratigraphically constrained estimations made in a least biased geostatistical manner, in advance of the tunnel. RQD, or a prediction of rock fractures, is handled by the faulting and folding modelling facilities. This is probably the more interesting issue to pursue, as the fractal nature from small scale fractures and joints, to large-scale faults, can now be characterised more convincingly.

Mar 8, 2011

By N Schofield

For the sampling of particulate materials in mineral exploration and mining, the fundamental sampling error (FSE) introduced by Gy is a measure of the constitutional heterogeneity of the sample lot and is expressed as the relative standard deviation of subsample grades of a particular mass. The FSE is presently regarded as an important indicator of quality for samples used in resource estimation. Constitutional heterogeneity describes an ideal state of heterogeneity with respect to all constituents of the lot such that the fundamental error among subsamples of a particular mass is minimised.In this paper, the term ‘sampling precision’ used in relation to mineral resource sampling usually refers to a statistic based on the assay results drawn from pairs of separate subsample splits of multiple sample lots. The pairs of splits are extracted after the lots have been prepared by crushing and pulverising to meet specified criteria of grain size and subsample mass. There is presently no generally accepted method of calculating the ‘sampling precision’ from such paired data but some form of the relative standard deviation that is consistent with definition of the FSE is preferred here. The work of Thompson and Howarth in the 1970s on geochemical analytical precision, which has been subjected to extensive examination and criticism by Stanley and Lawie (2007), and that of Francois-Bongarçon since the 1990s forms the background to the discussion in the paper.A significant aspect of the application of Gy’s sampling theory to sampling in gold deposits is the requirement that the fundamental error be maintained at less than ±20 per cent. The most important reason for this is to ensure that the effects of other sampling errors such as the grouping and segregation, and increment delimitation which can cause local and global biases in sampling are kept as small as possible. This paper is focused mainly on the quality of sampling in gold deposits and looks at an alternative to the use of a constant sampling precision applied to a collection of lots with varying average grade. A theoretical model for the FSE based on duplicate sampling is presented and the simulated results of the model are compared to practical outcomes of real duplicate pairs drawn from multiple sample lots. The goal of the work is to present a more informative analysis of duplicate sample data from multiple lots which may allow a more informed view of the potential for bias generating errors during sample preparation and processing.

Aug 22, 2011

By J. Marts

Underground longwall coal mining sections are operated as sealed gobs if the coal is prone to spontaneous combustion. Sealing along the gate roads during longwall face retreat limits the flow of fresh air (oxygen) into the gob and, thus, deprives the spontaneous combustion reaction of oxygen. In a project sponsored by the National Institute for Occupational Safety and Health (NIOSH), researchers at the Colorado School of Mines have used computational fluid dynamics modeling to simulate the flow of gases in sealed longwall gobs. The models were validated using measurements and observations from the field and demonstrate that targeted injection of nitrogen along the gate roads inby the face can be used to control the size and location of explosive methane clouds within the gob and to minimize or eliminate the explosion hazard resulting from the formation of flammable methane-air mixtures.

Sep 1, 2013

By Ali Azizian, Brian Hall

"Driven piles were selected to support the Fraser Heights Bridge bents. Piles were a key component of the top-down construction approach, which was adopted for minimizing potential impacts on an environmentally sensitive wetland. Project requirements mandated verification of pile capacities using dynamic methods. More than 40 Pile Driving Analyzer (PDA) tests were performed. The subsurface conditions were highly variable. On the east side, piles extended through loose sands, soft silts/clays, and two peat layers and were founded in glacial till-like soils at about 45 m depth. However, on the west side, till-like materials were so shallow that it was difficult to drive the piles sufficiently deep to obtain the necessary lateral support. This paper provides an overview of the geotechnical considerations of the bridge design and top-down construction approach, and expands on the presentation of PDA results and how they compared to pile capacity estimation methods and parameters recommended in the applicable design codes.INTRODUCTIONThe Fraser Heights Bridge (FHB) was a component of the Fraser Heights Connector (FHC), a 2 km section of the South Fraser Perimeter Road (SFPR), constructed as part of the Port Mann/Highway 1 (PMH1) Improvement Project. The FHC is located in northeast Surrey BC (Fig. 1).Two major design and construction determinants were: 1) a mandated tight schedule to provide a non-tolled alternative to a new toll bridge; and, 2) an obligation that construction had to occur with minimal impact on the environmentally sensitive wetland the FHB crossed, including limiting the footprint of the permanent and temporary works to less than 45 m2, and prohibiting construction access onto the wetland. Construction equipment was only allowed on the wetland on temporary trestles or on the finished structure. This latter requirement resulted in the bridge being constructed span by span, using a top-down approach."

Jan 1, 2016

By A D. Strand

The Coeur dÆAlene mining district in northern Idaho, USA is the second largest producer of silver in the world. The Proterozoic Revett Formation hosts most of the mesothermal Ag-Pb-Zn vein ore in the district; it consists of informally designated lower, middle, and upper members. All three members show up to an order of magnitude of southward thickening across the regionally significant Osburn fault. Changes in thickness of the Revett Formation across the Osburn fault reflect a major, down-to-the-south, crustal-scale fault that:was active during sedimentation, was periodically reactivated during the structural and metallogenic history of the district, and likely provided first-order control over regional fluid flow during mineralization events. Where vein structures intersect favourable strata, they produce rich ore; where vein structures cross unfavourable strata, they are poorly mineralised or barren. The most favourable host rock in the district is quartzite, which accounts for the large production from the quartzite-rich Revett Formation.The district has five main types of hydrothermal alteration:feldspar destruction, hydrothermal bleaching, carbonatisation, sulfidation, and silicification. Feldspar destruction is the most extensive and pervasive type of alteration, involving the district-wide absence of feldspar from Belt Supergroup rocks. Hydrothermal bleaching results from the destruction of hematite; it forms alteration envelopes that extend for tens to hundreds of metres into the wall rocks around many of the mineralised veins. Siderite alteration is most diagnostic of mineralisation, forming alteration envelopes that extend for tens to hundreds of metres into the wall rocks around all mineralised veins. Fine-grained arsenopyrite and/or fine-grained pyrite commonly form alteration zones adjacent to high-grade ore shoots that extend for metres to tens of metres into the wall rocks. Widespread silicification is most easily recognised by the presence of numerous quartz veins.

Jan 1, 2002

By H. H. Wober, P. J. Morgan

"The proposed classification of ore reserves based on geostatistical and economic parameters is designed to be used as a communication tool to identify for investors, bankers, and financial analysts the degree of risk associated with a specific class of ore reserves. The class designation identifies the degree of accuracy of the estimates for tonnage and grade of annual production volumes of ore. It thus enables decision makers to quantify the risks and uncertainties inherent to the ore reserve in achieving over-all economic goals and annual financial objectives.IntroductionDuring the evaluation, in 1980, of the Creede silver deposit in Colorado, U.S.A., as a potential bulk mining project, the authors were faced with the problem of conveying to senior management the risks and uncertainties that are implied by using common or conventional classification systems to categorize ""ore reserves"". The estimated numbers for tonnages and grade of the projected ore reserves represented the only entry for future revenue from the project. It was, therefore, necessary to convey to management the level of risk associated with those numbers when implementing further stages of development, and to convey what impact significant differences would have on the profitability of the project. The desire to quantify these risks led to a revised definition of ""ore"" and to a re-examination of the classification system of ""ore reserves"". Traditional methods for estimating tonnage and grade of reserves do not include a quantification of the errors of these estimates. The advent of geostatistical methods made this quantification possible. The proper application of geostatistical methods, with adequate geological input and a reliable set of sample data, is essential to its validity.Others have proposed a classification of ore reserves based on geostatistical parameters. Diehl and David (1982) recognized ""that concepts of proven, probable and possible have to be linked to the production rate or time horizon"". Royle (1977) had also addressed this problem. Forsyth (1987) pointed out that bankers are concerned with ""the probability that the variability will fall within a certain degree of accuracy"" especially for grade estimates, and would like to see grades expressed together with the error of the estimate at the 950Jo confidence level."

Jan 1, 1993

By S Sineva, E Jak, M Shevchenko, D Shishin

This study represents a part of comprehensive research aimed at integrating nickel into a thermodynamic database constantly developed at Pyrosearch. The behaviour of Ni in calcium-ferrite slags is considered. An integrated approach combining experimental and thermodynamic modelling methods has been employed to predict phase equilibria in the NiO-CaO-FeO-Fe2O3 system under oxidising conditions and in equilibrium with the metal FeNi phase. The compositions of liquid slags and coexisting solid solutions have been determined through the analysis of equilibrated and quenched samples by electron probe microanalysis technique (EPMA). The research results are presented in the form of liquidus projections on the corresponding phase diagrams, considering both oxidising and reducing conditions. The solubility of Ni in spinel, dicalcium ferrite and calcium oxide as well as solubility of Fe and Ca in Ni monoxide, have been examined under several atmospheric conditions. Additionally, the compositions of the NiO-FeO monoxide in equilibrium with metal phase have been studied. The experimental data not only support the outcomes of thermodynamic modelling but also validate the parameters of the applied thermodynamic models, thus confirming the reliability and accuracy of the integrated approach.

Aug 21, 2024

By Renan Barrio de Mendoza

"El presente texto señala la aplicación de nuevas tecnologías conceptos para reducir u optimizar el consumo de energía, como los costos de operación en los procesos metalúrgicos. Así, el uso eficiente de la energía en la actividad minera tiene su impacto en la sociedad -en tanto se emplee adecuadamente en las etapas del tratamiento del mineral. Cabe recordar que en las operaciones de reducción de tamaño de partículas es más barato volar que chancar, así como chancar que moler."

Jul 1, 2015