Search Documents

By R. W. Lewis

Spectrochemical procedures were developed using dc arc excitation for the determination, in parts per million, of 18 impurity elements in electrorefined beryllium and high-purity beryllium oxide. The metal samples were dissolved in dilute hydrochloric acid, evaporated to dryness, and converted to the oxide in a muffle furnace at 900° C. Germanium oxide was added as an internal standard for the determination of 15 of the elements, copper oxide for boron and molybdenum, and neodymium oxide for calcium. The average coefficient of variation was 11 percent with the exception of copper, which averaged about 43 percent.

Jan 1, 1962

By R. J. R. Schaller

NO. 3 winze, the sixth shaft to be sunk on the San Antonio property, is practically a duplicate of No. 3 shaft, which was the main shaft prior to the installation of the larger hoisting equipment in 1939. It is collared on the tenth, or 1,500-ft., level, and goes down vertically to the sixteenth, or 2,500-ft., level, with a loading pocket, spill pocket, and sump below this. It is 1,000 feet east of No. 3 shaft. All ore, men, and materials are handled through the latter. The winze location with reference to the rock formation is shown in Figure 1. (In plan, this section strikes N.30°E. and cuts most of the main orebodies of the mine normal to their strike.) It is collared eighty feet inside the footwall contact of the basalt and cuts through it before reaching the eleventh level. In this location there will be no ore tied up in shaft pillars, as the closest ore to the shaft is on the tenth level, and here it is eighty feet northeast of the collar. The winze headframe and hoist-room straddle the main haulage to the No. 3 shaft, on the tenth level (see Figure 2). At no time during the excavation for the headframe and hoist-room was the general routine work of this haulage held up.

Jan 1, 1941

By A. R. Chambers

Malagash received its name from the Indians many years ago on acco.unt of its turbid (milky) waters, although,' the red men did not appreciate the significance of this turbidity, and were, of course, entirely ignorant of the crystal beds of pure salt that lay beneath their feet. The salt lake of the Mississippian, or Lower Carboniferous period, in which these beds occur, was apparently a large one, for there is evidence of its existence at intervals all the way from Sydney, Cape Breton, to St. John, New Brunswick, 300 miles as the crow flies, and there is no knowing what its other dimensions may have been, as much of this horizon is now buried on the one side beneath the waters of the Gulf of St. Lawrence, and on the other underneath the Atlantic ocean. About midway of the area and underlying the counties of Colchester and Cumberland, there occurs a synclinal basin of which the Malagash salt outcrop forms only a small portion of its northern limit. This basin has been described very fully by A. C. Hayes. (1) The operations carried on at Malagash since Hayes wrote his report have brought to light very little in the way of new geological data, except to confirm his pre-dictions as to the probable faulting of the salt strata, and the effect which these faults would have on mining operations.

Jan 1, 1924

By John A. Richards

This paper is one of a series being published by the Bureau of Mines on mining methods and costs. It describes briefly the manner in which slusher hoists and scrapers are used in connection with clock-caving methods at the Emma Nevada mine of the Consolidated Coppermines Corporation, Kimberly, Nev. Kimberly is in the Robinson mining district, White Pine County, 7 miles west of Ely. The district is served by the Nevada Northern -Railroad, which branches from the main line of the Southern Pacific at Wells, Nev., 140 miles north, Paved U. S. Highway 50 from Salt Lake City, Utah, to Reno, Nev., passes through Ely. The altitude at the collar of the Emma Nevada shaft is 7117 feet. The surrounding hills are covered with a sparse growth of juniper, pinon, and mountain mahogany.

Jan 1, 1940

By S. L. Weber, D. E. Banks

"Silicosis was first reported by the ancient Greeks and is apparently as old as human history. The prevalence of this illness peaked in the last half of the 19th century and the early part of this century, when mechanized industry was developing and the relationship between dust exposure and disease was less well understood. Yet, even today in devel-oped countries, sporadic outbreaks of silicosis occur when workers are consistently exposed to silica particles of respir-able size (0.5 to 5.0 µm in diameter) at levels exceeding those recognized to be safe.Silicon dioxide or silica. is the earth's most abundant mineral. Silica is considered to be either free (i.e.. unbound to other minerals) or combined. Minerals with high amounts of free silica include quartz (including granite) flint. Chert, opal, chalcedony, and diatomite. Combined forms of silica are called silicates and include, among others, asbestos talc and kaolin.In the crystalline form, silica exists as quartz, cristobalite, and tridymite (Fig. 28). Of these quartz is ubiquitous in the environment and occurs as sand and as a part of many rocks. Cristobalite and tridymite occur naturally in lava and can be formed by the heating of quartz or amorphous silica. Cristo-balite is more tibrogenic than quartz. Amorphous silica is noncrystalline and, therefore, is relatively nontoxic and does not cause silicosis. It occurs as diatomite (skeletons of pre-historic marine organisms) or as vitreous silica (glass), the result of carefully melting and then quickly cooling free crystalline silica. Heating diatomite with or without alkali (a process known as calcining), forms cristobalite and adds the respiratory toxicity of free crystalline silica.There are many opportunities for occupational exposure to respirable crystalline free silica. Some of the commonly en-countered occupations in which the risk of silicosis exists are reported in Table 20.Silicosis. the pulmonary disease caused by the inhalation of silica particles of respirable size, is most commonly cate-gorized by findings on the chest radiograph. The most typical presentations simple silicosis and progressive massive fibrosis appear different radiologically but are grouped under the category of classic silicosis because they are a part of the radiographic spectrum of this illness. Radiographically, simple silicosis appears as small (less than 10 mm in diameter), rounded opacities, typically predominant in the upper lung zones. Progressive massive fibrosis is the result of the coalescence of these small nodular opacities and appears as larger opacities (more than 10 mm in diameter), again typicallydistributed in the upper lung zones."

Dec 1, 1995

By Raja V. Rarnani, Robert L. Frantz

"Scientific, engineering, and biomedical research teams synergystically developed major topical research areas in the Respirable Dust Center. Descriptions of their interactions and resulting accomplishments demonstrate how cooperative research within and among these study groups benefits the overall respirable dust research and practical application needs of the mineral industries.The development of a state-of-the-art small animal inhalation exposure facility suitable for studies of fresh and aged coal mine dust, a major goal of this research group, will contribute toward the GTCRD goal of advancing the understanding of causative mechanisms for the occupation-related lung impairments and the airway diseases of mine and mill workers. Such understanding includes improved definition of the role of various aspects of the lung environment (e.g., surfactant and the mucociliary system) in the disposition and toxicity of respirable dust, comprehensive characterization of the role of the pulmonary alveolar macrophage (PAM) and its secretory products on the development of dust-related lung disorders, and an expanded search for methods to reduce the toxicity of respirable dust both before and after it enters the lung. The National Academy of Sciences has recommended, in Measurement and Control of Respirable Dust in Mines, that respirable dust research should include study of the behavioral and constitutional factors affecting individual susceptibility to workers' pneumoconiosis occupational disease and the development of methods for detecting the potential onset of pneumoconiosis earlier and more conclusively than can be done using X-ray methods. These recommendations have guided the research group in its goals of establishing and disseminating a scientific protocol for standardizing the inhalation testing for all research objectives within the Generic Center which involve small animal exposures and implementing the infrastructure necessary to make lung tissues obtained during inhalation studies available to all researchers within the Generic Center."

Jan 1, 1995

By Robert S. Warfield

The Federal Bureau of mines and U.S. Geological Survey conducted exploratory investigations and geologic mapping in the Wishbone Hill district of the Matanuska coalfield almost continuously from 1942 through 1958. These investigations delineated reserves of high-volatile bituminous coal necessary to supply the rapidly expanding military and civilian requirements in the Anchorage area. This report describes the program conducted by the Bureau of Mines from 1949 through 1958, and briefly summarizes previous investigations, the results of which have already been published. The coal-bearing structure on both the north and south limbs of the prominent Wishbone Hill syncline was explored by 8,719 feet of churn drilling and 25,460 feet of diamond-core drilling. A total of 33 holes were drilled ranging in depth from 60 to 2,114 feet. To supplement the drilling operations, bulldozer and dragline trenching were undertaken at key locations; about 25,000 cubic yards of dragline trench were excavated in the vicinity of the old Premier mine.

Jan 1, 1962

By Richard L. Ash

A question that frequently arises during litigation concerned with accidents or alleged damages involving blasting is "were the explosives used according to the best known standards"" The question is not confined to only law suits, however, but also everytime poor blasting results occur. Unfortunately, general guidelines that can be used to define what may be considered as proper practice have not been established by any responsible body upon which to base a reliable Judgment; more often than not decisions are made primarily according to personal opinion.

Jan 1, 1975

By N. O. Lotter

The connection between mineralogy and metallurgical performance in a plant was recognised long ago (Gaudin, 1939; Petruk, 1976; Petruk and Hughson, 1977; Cabri, 1981; Petruk and Schnaar, 1981; Kinloch, 1982; Peyerl, 1983, Baum et al 1989 for example). The modern toolbox that we now routinely use for flowsheet development took decades to develop (Lotter et al., 2002; Baum and Lotter, 2004; Lotter, 2011 for example). Many workers contributed considerable time and effort to this overall mission of connecting sampling, mineralogy and mineral processing to integrate the flowsheet development activities. Certain key milestones marked this journey, such as Gy’s treatise on the sampling of particulate materials in 1979, which was later added to by François-Bongarçon, Pitard, Minnitt, and Holmes for example. The development of QEM*SEM by Gottlieb et al. of the MLA by Gu et al. constituted a huge leap forward in accuracy and mineral measurement capacity, as well as a reduction in standard errors of mineral characterisation. The advancement of the microprobe to an automated platform made a significant difference to detailed compositional mineralogy. This led to a strong position from which to draw meaningful processing implications from the mineralogical data. Reproducible flotation testing and reliable plant survey material for characterisation was dealt with by, amongst others, High Confidence Flotation Testing ( Lotter, 1995: Runge, 2010, and Bradshaw, 1997); and Statistical Benchmark Surveying (Lotter, 2005), with earlier prototypes which were steadily improved (Lotter, 1994; Restarick, 1976). The sterling work of Napier-Munn in engaging sound statistical methods with mineral processing led to the successful design and use of methods that could identify and quantify small recovery gains in plant scale trials. This history and present capability are reviewed, including leverage into asset management.

Jan 1, 2018

By C. Yi, M. Onifade, B. Genc, S. Dineva, T. Zvarivadza, M. Khandelwal

Deep hardrock mines worldwide increasingly face rockbursts as mining depths increase. These events result from the accumulation and sudden release of stress, causing rockmass damage and posing major safety and operational challenges. This paper focuses on destress blasting as a critical strategy to mitigate rockburst hazards. Although limited practical experience exists in Swedish deep hardrock mines, international case studies demonstrate that, when well implemented, destress blasting redistributes peak stresses by promoting controlled fracturing around mining excavations. The success of such techniques is highly dependent on site-specific factors such as stress regime, rockmass brittleness, structural geology, and blast layout. Although destress blasting is especially effective in massive, brittle rock under high stress, typical conditions for strainburst prone environments, its design cannot rely solely on numerical models. Simulations can offer preliminary evaluation of stress redistribution trends and guide early design assessments but their current limitations, including sensitivity to input data and simplified fracture mechanics, mean they are best used as supplementary tools rather than final decision-makers. Field trials, supported by microseismic analysis and fracture mapping, remain essential for validation. The study critically synthesises international experiences and presents a structured framework for destress blasting design, offering practical and academic perspectives aligned with Swedish geological conditions to support safer and more efficient application in deep hardrock mines.

Jun 27, 2025

By A. L. Pierce

This paper describing the mining practice at the Spring Hill mine of the Montana Mines Corporation, Helena, Mont., is one of a series issued by the Bureau of Mines on mining methods and costs in various districts. Its purpose is to summarize improved methods whereby lower costs have recently been obtained. These improvements are principally the adoption of a modified sublevel stoping method of mining the use of grizzlies underground improvements in haulage, and rage bonuses. The Sprint Hill, Trine is situated in Grizzly Gulch, 3 miles southwest of the city of Helena. Helena is on the links of the Northern Pacific and the Great Northern Railways; and the East Helena smelter of the American Smelting and Refining Co. to which the concentrates from the mine are shipped, is but 6 miles east of Helena. The mine is probing 150 to 200 tons of gold ore per day, with an underground crew of about 40 men.

Jan 1, 1931

By C. D. Ashley, X. P. Garzon-Villalba, R. M. Lopez, T. E. Bernard

Federal standards for refuge alternatives (RAs) mandate that they not exceed a Steadman apparent temperature (AT) of 95 °F (35 °C) at an assumed metabolic rate of 325 W, a limit that appears to be arbitrary. Occupants in an RA spend most of their time at rest (a metabolic rate less than 325 W), and thermal equilibrium can likely be maintained at an AT > 35 °C. The purpose of this study was to examine the upper limit of sustainable heat stress during 4- and 8-h exposures at rest. Five men underwent five 4-h trials (phase 1: AT range 39 to 49 °C, 90% rh) and five 8-h trials (phase 2: AT range 46 to 56 °C, 90% rh) in a semi-recumbent position. Descriptive statistics for gastrointestinal temperature (Tgi), heart rate (HR), systolic and diastolic blood pressure (SBP and DBP), sweat rate, fluid intake, urine color, urine specific gravity (USG), and changes in body mass are reported. Mean Tgi for all trials ranged from 36.9 to 37.3 °C, and mean HR for all trials ranged from 61 to 75 bpm. To determine the effects of increased heat exposure, differences in heat strain between 4- and 8-h trials were examined via repeated measures analysis of variance (ANOVA). As AT increased, there were no significant changes in ΔTgi and ΔHR from 1 to 4 h in the 4-h and 8-h trials. During the 8-h trials, as AT increased, there was a difference in ΔTgi between 4 and 8 h. In conclusion, there was support for sustainable exposures resulting in no significant increase in physiological strain at an AT greater than 35 °C AT, with a sustainable limit (no increases in Tgi due to increases in AT) below 46 °C AT. Although the participants were not representative of coal miners, the results provide support for sustainable exposures greater than 35 °C AT at an average metabolic rate of 155 W.

By C. D. Ashley, X. P. Garzon-Villalba, R. M. Lopez, T. E. Bernard

Federal standards for refuge alternatives (RAs) mandate that they not exceed a Steadman apparent temperature (AT) of 95 °F (35 °C) at an assumed metabolic rate of 325 W, a limit that appears to be arbitrary. Occupants in an RA spend most of their time at rest (a metabolic rate less than 325 W), and thermal equilibrium can likely be maintained at an AT > 35 °C. The purpose of this study was to examine the upper limit of sustainable heat stress during 4- and 8-h exposures at rest. Five men underwent five 4-h trials (phase 1: AT range 39 to 49 °C, 90% rh) and five 8-h trials (phase 2: AT range 46 to 56 °C, 90% rh) in a semi-recumbent position. Descriptive statistics for gastrointestinal temperature (Tgi), heart rate (HR), systolic and diastolic blood pressure (SBP and DBP), sweat rate, fluid intake, urine color, urine specific gravity (USG), and changes in body mass are reported. Mean Tgi for all trials ranged from 36.9 to 37.3 °C, and mean HR for all trials ranged from 61 to 75 bpm. To determine the effects of increased heat exposure, differences in heat strain between 4- and 8-h trials were examined via repeated measures analysis of variance (ANOVA). As AT increased, there were no significant changes in ΔTgi and ΔHR from 1 to 4 h in the 4-h and 8-h trials. During the 8-h trials, as AT increased, there was a difference in ΔTgi between 4 and 8 h. In conclusion, there was support for sustainable exposures resulting in no significant increase in physiological strain at an AT greater than 35 °C AT, with a sustainable limit (no increases in Tgi due to increases in AT) below 46 °C AT. Although the participants were not representative of coal miners, the results provide support for sustainable exposures greater than 35 °C AT at an average metabolic rate of 155 W.

The importance of proper planning, preparation, and execution of a steady state sampling campaign for metallurgical plant assessment must not be underestimated. Careful planning can increase the amount and reliability of information from an optimum number of samples and fully utilize available plant data. It requires specification of the data required, determination of run duration sampling frequency, the selection, modification and testing of sample points and cutters, as well as organisation and briefing of plant and sampling personnel. Preparation immediately prior to sampling, the conduct of the sampling campaign itself and procedures to handle the collected samples and information are discussed. Cutter design, fabrication and use are described in detail, and typical sampling situations, for ball mills, classifiers, pipes, launders, flotation cells and thickeners are considered individually. Measurement of pulp flow rate can often resolve difficult mass balance problems, and discussion of convenient techniques is included.

Jan 1, 1976

After some 50 years of worldwide research in relation to coal pillar mechanics and design as well as numerous workshops and technical papers related to these issues there is still some significant disagreement as to the approach one should adopt in the assessment and design of a coal pillar. Of course there are many different types of coal pillars that fulfil a wide range of roles at any particular mine and in this instance it is appropriate to have a 'tailored' approach for each pillar type in relation to the role it fulfils. However where it can become very difficult for the mine operators is when various researchers or consultants use or recommend significantly different approaches for the same type of pillar fulfilling the same role. By 1999 two pillar design techniques had been developed specifically for the Australian underground coal mining industry (ie The University of New South Wales Pillar Design Procedure, UNSW PDP and Analysis of Longwall Tailgate Serviceability, ALTS) and several other pillar design techniques were being practiced by individual consultants. The Australian industry hoped to resolve the issue of what technique to use for each pillar type and role, when it funded UNSW in 2000 to develop a 'Systems Approach to Pillar Design'. The findings of the abovementioned project were published in 2005 and while every attempt was made by UNSW to include the views of various local and overseas researchers and consultants it would be fair to say that a unified approach to pillar design in Australia was not adopted as a result of that project. This is the experience of one country where there has never been one central group solely undertaking such research in relation to pillar design (such as the Chamber of Mines in South Africa). This paper explores the Australian experience in terms of pillar research and what that experience may offer to researchers in Australia and other countries. At the First Australasian Ground Control in Mining Conference (2003) the first 'update' of the ALTS Design Methodology (ie ALTS II) was presented. In subsequent years the ALTS database was continually updated and significantly expanded such that it now includes detailed information in relation to both the tailgate (148 cases) and maingate belt road (58 cases). In addition to tailgate roof support and chain pillar design, the current version of ALTS (referred to as ALTS 2009) includes a maingate belt road roof support design module. This paper is also intended to update and summarise the development and application of the ALTS Design Methodology for longwall gateroad design over the last decade both directly and in the context of coal pillar research conducted in Australia over the last 15 years.

Nov 25, 2010

By M Taylor

The Project Specification and Technical Requirements documents associated with several recent large road tunnel projects within Australia have specified the application of AS/IEC 61508 – FunctionalSafety of Electrical/Electronic/Programmable Electronic Safety Related Systems at very high performance levels for the various control and fire life safety systems associated with such facilities.This paper seeks to explore the implications of referencing this standard within the road tunnel services context in terms of practicality, complexity and cost, whilst providing some examples of how a high safety integrity level (SIL) level can theoretically be achieved given current hardware availability.

Mar 8, 2011

By Christopher Mark

"Many problems in rock mechanics are limited by our imperfect knowledge of the material properties and failure mechanics of rock masses. Mining problems are somewhat unique, however, in that plenty of real world experience is generally available and can be turned into valuable experimental data. Every pillar that is developed, or stope that is mined, represents a full-scale test of a rock mechanics design. By harvesting these data, and then using the appropriate statistical techniques to interpret them, mining engineers have developed powerful design techniques that are widely used around the world. Successful empirical methods are readily accepted because they are simple, transparent, practical, and firmly tethered to reality.The author has been intimately associated with empirical design for his entire career. But where his past papers have described the application of individual techniques to specific problems, the focus of this paper is the process used to develop a successful empirical method. A six-stage process is described:1. Identification of the problem, and of the end users of the final product2. Development of a conceptual rock mechanics model, and identification of the key parameters in that model3. Identification of measures for each of the key parameters, and the development of new measures (such as rating scales) where necessary4. Data sources and data collection5. Statistical analysis6. Packaging of the final productEach of these stages has its own potential rewards and pitfalls, which will be illustrated by incidents from the author’s own experience. The ultimate goal of this paper is to provide a new and deeper appreciation for empirical techniques, as well as some guidelines and opportunities for future developers."

Jan 1, 2015

By Stephen A. Swan

Certain types of mobile surface mining equipment are required to be equipped with rollover protective structures (ROPS) capable of protecting the operator in case of a rollover accident. The Bureau of Mines has developed ROPS performance criteria for wheeled front-end loaders. This report reviews the development of rollover test procedures and subsequent testing of ROPS for 52,000-, 286,000-, and 390,000-lb gross vehicle weight (GVW) loaders. The program consisted of both dynamic (roll) and static tests to assist in the development of the ROPS performance criteria. Each test included extensive instrumentation and photographic documentation to fully evaluate the performance of the ROPS. Data summarizing side, longitudinal, and vertical force and deflections are included. The data indicate that for loaders in excess of 240,000 lb, GVW, a side force-to-mass ratio of 1.0 and an energy-to-mass ratio of 6.0 appear to be adequate criteria to protect an operator in the event of a 5400 rollover. For smaller machines, Society of Automotive Engineers (SAE) 11040 performance criteria provide adequate protection. Longitudinal loading, though not ad-dressed in previous ROPS performance criteria, was shown to be a potentially significant factor in ROPS failure. Longitudinal loading and energy criteria equal to 80 pct of side loading criteria are recommended.

Jan 1, 1988

By Jasper L. Stuckey

GEOGRAPHICALLY, North Carolina consists of three divisions, the coastal plain on the east, the piedmont plateau in the center, and the Appalachian mountain region on the west. Geologically, the State may be divided into two main divisions, an eastern or coastal plain region, and a western or piedmont plateau and mountain region. The eastern region is underlain with unconsolidated sands, clays, marls, and shell limestones varying in age from Cretaceous to Recent. The western region is, in general, underlain with gneisses, schists, slates, sheared volcanics, and igneous intrusives of Pre-Cambrian age. In the mountain and upper piedmont portion of the western region are several areas of irregularly metamorphosed sediments of early Paleozoic age. Throughout the piedmont plateau and a part of the mountain portion of the western region, important areas are underlain with igneous intrusives of late Carboniferous age. Along the eastern edge of the piedmont plateau are two narrow belts, trending northeast-southwest, underlain with sediments of upper Triassic age. Although North Carolina contains a

Jan 1, 1947

By P Kittler

In the spectrum of mining-related disciplines, geometallurgy sits between resource geology and metallurgical engineering. Unlike its neighbours, it is a relatively young discipline and its concepts, procedures and techniques are still evolving. Relevant geometallurgical issues differ from one deposit to the next so there is no single template that can be used in all situations, meaning that geometallurgy programs are nearly always customised and tailored to the deposit and the situation.Over time, a number of key mistakes are seen to emerge regularly. The eventual impact of these mistakes can vary from suboptimal performance of mine and plant to complete failure of the operation. For instance, poor characterisation of ore lithologies and their spatial distribution can have negative impacts on processing plant throughput. However, when combined with failure to identify critical blending constraints it can result in a totally inoperable plant.A number of common mistakes committed during geometallurgical programs are discussed and some preferred alternative approaches are suggested

Sep 5, 2011