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Calcium carbonate has three polymorphs: calcite, aragonite, and vaterite. Needlelike aragonite CaCO3 with a high ratio of length to diameter (aspect ratio) is widely used in plastics, rubber and ceramics as a filler and in pigments and paints as a carrier. This paper investigated the influence of H3PO4 dosage, reaction temperature, CO2 flow rate, and initial Ca(OH)2 concentration on formation of needlelike aragonite CaCO3. It was found that the presence of H3PO4 in Ca(OH)2 suspension resulted in rapid formation of (Ca5(PO4)3(OH)) crystal nuclei, which facilitated nucleation and growth of aragonite CaCO3 on the formed (Ca5(PO4)3(OH)) crystal surfaces. The results revealed that H3PO4 addition of P/Ca of 0. 2~0. 3, high temperature of 75~85 °C, low CO2 flow rate and initial Ca(OH)2 solid concentration of 1. 5 %~5. 6 % are beneficial to formation of aragonite. Well crystallized needlelike aragonite CaCO3 whiskers with length > 20 µm and aspect ratio > 15 were directly synthesized.

Jan 1, 2014

By Denis Tepavac, Mark Trim

Structural performance of fiber reinforced concrete (FRC) depends on its ability to carry tensile forces after cracking. Australian Standards AS5100-2017 and AS3600-2018 are the only available design standards that establish a test procedure to determine strength and toughness of an FRC in direct tension. Direct tensile testing of fiber reinforced shotcrete samples was performed to determine if the model and guidelines in AS5100/3600 were applicable to shotcrete; all previous testing was from cast samples. In addition to direct testing, micro CT-scanning was also performed. The paper presents tests performed, results, and how the tests could be used on future projects. In addition, a brief summary is provided of the guiding structural mechanics used for estimating residual tensile strength and test methods utilized to verify those estimates.

Jun 13, 2023

By F. Qi, T. Frišcic, C. Mottillo

"One of the principal goals of modern industry is to minimize the environmental impact and increase the materials- and energy-efficiency of transforming raw materials into valuable products. This paper will highlight our latest laboratory-scale research in low-energy, low-solvent reactivity of metal oxides and their conversion into popular metal-organic frameworks (MOFs), zeolitic imidazolate frameworks (e.g. Basolite® Z1200 component ZIF-8), and metallodrugs (e.g. bismuth subsalicylate, active component of Pepto-Bismol®). Mechanochemical ion- and liquid-assisted grinding (ILAG) and ""accelerated aging"" techniques will be presented, along with novel low-energy and solvent-free approaches, inspired by geological weathering processes, for converting metal oxides into metal-organic materials. INTRODUCTIONThe development of environmentally-friendly processes, which would in the same time be more materials- and energy-efficient than the existing ones, is one of the central concerns of modern chemical research. In that sense, the focus of the chemist has been mainly on the preparation of carbon-based organic molecules and adaptation of traditional organic synthesis to the recently delineated ideals of Green Chemistry. However, there is a growing realization within the chemistry community that significant energy, materials, and ecology-related benefits can be achieved and, indeed, targeted in the transformations of materials that are typically associated with inorganic chemistry and minerals processing. The principal aim of this highlight contribution is to illustrate how, through the use of approaches associated with solventfree chemistry and mechanochemistry (James et al., 2012), one can develop a clean and efficient system of chemical and materials transformations involving oxide precursors that normally belong to the realm of inorganic chemistry and mineral processing. In particular, this contribution will provide an overview of the recently developed mechanochemical and solvent-free reactivity of metal oxides towards small organic molecules. These mechanochemical reactions, including the methods of liquid-assisted grinding (LAG, Frišcic & Jones, 2009) and ion- and liquid-assisted grinding (ILAG, Frišcic, 2010), have so far provided a radically different means to construct advanced metal-organic materials (e.g. porous metal-organic frameworks, [MOFs] or metallodrugs) by rehabilitating metal oxides as precursors, eliminating the use of bulk organic solvents, and avoiding the use of high temperatures."

Jan 1, 2012

By O. Babak, O. Leuangthong, M. A. Cuba

Integration of data from multiple sources and/or multiple scales is a common, yet challenging aspect of geostatistical resource modeling. Common approaches to data integration are based on a cokriging framework that assumes a consistency of scale in the information that leads to a requirement to composite the data prior to model construction. It is well known that the geostatistical model parameters are scale dependent. In particular, the volume variance of integrating these various scales has a direct impact on the semivariogram that should be used in model construction and/or the assessment of volume-variance relations as it affects resource estimation. This paper reviews and compares two different approaches for semivariogram upscaling. The first approach is the scaling laws. It is an empirically derived approach, involving several simplifying assumptions, one of which is a strict assumption of invariance of the semivariogram shape. The second approach is a theoretically derived direct upscaling of the semivariogram. This approach has been around for a number of years, but is seldom implemented due to software limitations. In this paper, we present a numerical integration approach to facilitate direct semivariogram upscaling. The advantage of direct upscaling over the scaling laws approach is shown by considering a synthetic example and a case study. Further, in the case of multiple codependent random variables, the extension of the direct semivariogram upscaling to the cross semivariograms is derived and an upscaled consistent linear model of coregionalization is presented.

Jan 1, 2013

By R. Pandey, G. Elie, E. Sarver

Respirable crystalline silica (RCS) is generally considered the most hazardous constituent of coal mine dust, and a new federal rule is expected to further limit exposures in U.S. mines. For regulatory purposes, RCS is monitored by collecting filter samples, which are analyzed for quartz (the predominant form of RCS in coal mines). The analysis is done using Fourier transform infrared spectroscopy (FTIR) in a centralized laboratory. To enable more timely results, National Institute for Occupational Safety and Health (NIOSH) mining researchers developed a directon- filter (DOF) FTIR analysis method and free FAST software that can be used in the field. For samples collected under specific conditions, FAST processes the FTIR spectral data to determine quartz mass. While the DOF FTIR method is not approved for regulatory RCS monitoring, it could be useful for engineering purposes, such as to evaluate mining parameters or new dust controls. This field study demonstrates how the method, including FAST, can be applied using low-cost, widely available sampling components. It further demonstrates how quartz percentage can be estimated in the field, by pairing a continuous personal dust monitor with a filter sampler.

Jun 1, 2025

By Michael Somerville, Paul Voigt, Chunlin Chen, Alistair Burrows

To date, many types of primary concentrate have been smelted using the ISASMELT™ technology, with annual smelting of copper concentrate alone exceeding 7 million tonnes. Most of this material could best be described as chalcopyrite concentrate, owing to the predominance of copper attributable to this single mineral. Chalcopyrite concentrates lend themselves readily to smelting with a fayalite slag, and producing a matte containing 55–65 wt% Cu. However, the ISASMELT™ technology also stands ready to meet future copper demand through the treatment of new types of concentrates containing relatively low iron and high silica levels. Various slag systems have been considered for direct-to-blister smelting. They have been evaluated computationally, using the MPE thermodynamic modelling package, and practically, at pilot scale. The lime-silica-iron oxide slag was found to have the lowest slag make, lower dissolved copper and hence lowest copper losses. Based on the outcomes of the modelling and pilot scale testwork a future smelter flowsheet has been defined, comprising a single ISASMELT™ direct-to-blister furnace, an electric slag cleaning furnace, and appropriately designed anode furnaces.

Mar 1, 2017

By W. G. Davenport

Smelting oxidizes Cu-Fe-S concentrate to matte. Converting oxidizes this matte to metallic copper. Smelting and converting are, therefore, part of the same oxidation process. It would seem natural, then, that smelting and converting should be combined to produce metallic copper in one step. This would: (a) maximize S02 capture by restricting S02 emission to a single, continuous source (b) minimize industrial oxygen and fuel requirements (c) minimize cost. This chapter discusses one step, direct-to-copper flash smelting as it is practiced in 2000. It then uses. the matrices of this book to determine: (a) the industrial oxygen and oil requirements of direct-to copper flash smelting (b) the distribution of Cu between metal and slag during direct-to-copper flash smelting. It concludes that direct-to-copper flash smelting: (a) captures?S02 efficiently from its single continuous stream of SO2 off gas (b) minimizes oxygen/oil consumption but: (c) sends -114 of its Cu-in-feed to slag.

Jan 1, 2001

By J. E. Urosek

Decisions made during a response to a mine fire or an explosion greatly affect the final outcome. The safety of miners should be the primary concern with accounting for all of the miners the first issue for resolution. If miners have not safely evacuated from the mine, the last known location of the miners at the time of the event and anticipated travel routes are primary exploration areas. After the mine is evacuated, there are many very important decisions that must be made quickly and often under great stress. It is critical that the mine operator establish an orderly method to direct the mine emergency response. Designation of a Command Center, staffed with personnel charged with developing plans, is a common method of establishing control. Scheduling of key mine managers will be critical, since decisions must be made 24 hours a day and people working for extended periods with little or no sleep do not always make clear or cognizant decisions. Internal communications, passing information on to subsequent shifts, and external communications with families and media must be accurate and timely. Assembling resources for responding to the mine emergency is critical for an effective response, and pre-planning can pave the way to a successful recovery. Sampling mine gasses and accurately determining the composition of gas mixtures is a common tool used to develop response plans in all fires and explosions. It is essential that preparations for emergency situations are made well in advance of a disaster. Effective communications are essential for mine management to successfully respond to a mine emergency. This paper discusses some considerations which need to be addressed in directing a response to a mine fire or explosion.

Jan 1, 2009

By NARAYAN K. BHAGAT, ARVIND K. MISHRA, Aditya Rana, M. M. Singh

The paper presents an innovative directional controlled blasting (DCB) technique for excavating unstable slopes along the Konkan railway in India without disturbing the traffic. New empirical formulae for small geometry blasting to estimate burden and throw were developed. A unique sequence of firing and excavation with powder factor varying between 0.04 and 0.39 kg/m3, irrespective of the actual free face, was used for rock blasting. The process controlled the throw of blasted material over the track and resulted in a smooth and stable wall. The slope angle was changed from 80–82 to 45–47 degrees, and possible wedge, planar and toppling failures were eliminated. No incident of rockfall and slope failure along these slopes has been observed after the stabilization.

By Yi Tan, Kazuki Morita, Yaqiong Li

Molten Si-Al alloy, with the addition of Sn, was used for metallurgical grade Si purification by a low-temperature solidification method, with the aim of improving the recovery rate of Si. In this ternary melt, bulk Si was grown with a planar front by a directional solidification process under a well-controlled thermal gradient and growth rate conditions, thereby reducing the contamination of solvent metals. Effects of cooling rate, amount of Sn addition, and temperature gradient on the quality of bulk Si were determined. The criterion for constitutional supercooling for single-phase growth from multicomponent melts was employed to evaluate the growth process.

Jan 1, 2015

By Arthur Phillips

THE study of anisotropy in metals has been greatly stimulated in recent years by the rapid development of X-ray methods for determining the crystallographic relationships of wrought and annealed materials. Prior to this time the knowledge regarding the directional properties of commercial alloys consisted almost exclusively of observations of a practical nature made during the fabrication of metal objects, supplemented by a limited number of mechanical tests on specimens cut at various angles to the direction of working. Such observations clearly indicate that the common methods of cold-working metals cause both a crystallographic and a mechanical fibering varying in character and degree according to the nature and extent of the deforming process. Even after annealing, following certain not too well known combinations of reductions and anneals, a preferred orientation may exist, thereby constituting a residual fiber effect sufficiently pronounced to manifest directional properties. With the application of the X-ray the experimental horizon was extended chiefly because the study of anisotropic metals promised to offer direct and quantitative evidence regarding the involved mechanism of fragmentation and plastic flow. As a natural consequence the intensive studies in this direction have yielded a vast accumulation of data of ultimate potential value. Unfortunately, however, as is commonly the case in entering a virgin field of experimentation, many of the data cannot be molded into complete and coherent form because of the many unrelated conditions of the experimental projects. Again, the results of the study of single crystals have been rather naturally but at times indiscriminately applied to polycrystalline metals. Furthermore, sweeping statements have been made regarding the behavior during working and annealing of metals and alloys, entirely on the basis of similarity in lattice arrangement. There is abundant reason for believing that relatively small concentration variables, differences, in magnitude and distribution of applied stresses, and the character of associated annealing treatments may in some cases greatly influence the mechanics of flow and consequently largely determine the final structural characteristics of the metal.

Jan 1, 1932

By E. C. Bohlen, H. l. Burghoff

THE work reported in this paper was carried out to supplement the existing information concerning directional properties and recrystallization textures of annealed brass sheet and strip. These characteristics are of direct interest when the forming and drawing properties of such material are being considered. Among those who have made contributions in this field are Bass and Glocker;1 Bauer, Göler and Sachs;2 Phillips and Samans;3 Pratt;4 Price;5 Cook;6 Richards;7 Brick;8 and Brick and Williamson.9 These investigators have found, in general, that in brass strip that shows directional variations in properties, tensile strength has a minimum value and elongation has a maximum value at 45° to the rolling direction. The most pronounced directional properties have been found in material given the greatest reductions in rolling followed by high annealing temperatures. Recrystallization texture of brass has been variously reported as (113)[112], (001)[100], and a combination of (110)[115] and traces of the primary rolling texture, (110)[112]. The directional studies have been very informative, but actual tests appear to have been confined to material in its final condition. Tests at intermediate stages have received little attention although previous history of some materials has been partly considered. Perhaps the most comprehensive investigation was made by Cook,6 who studied the directional properties of 70-30 brass strip for which the final and penultimate, or next to the last, anneals and the final reductions were varied. He found that, for any given combination of penultimate anneal and final reduction, the tendency toward the development of directional properties was reduced as the temperature of the final anneal was decreased. In addition to drawing cups and making tensile tests of the finished material at various angles to the rolling direction, he measured the frequency and the angles of twins in grains for several specimens. Plots of his twin counts showed directionality for the materials that produced eared cups. TEST MATERIALS AND EQUIPMENT For this investigation, one commercial heat of 68-32 brass was cast in the form of bars for cold-rolling, 13 ½ in. wide and 1 ½ in. thick. The analysis was as follows: 68.83 per cent copper, 0.04 per cent lead, 0.01 per cent iron, 31.12 per cent zinc (by difference). The bars were so processed to the final thickness, 0.020 in., as to obtain on this thickness all possible combinations of the variables listed below except those involving the sequence of 84 per cent penultimate reduction and 84 per cent final reduction: I. Penultimate reductions of 37 per cent, 50 per cent and 84 per cent; 2. Penultimate anneals at 800°, 900°, 1050° and 1200°F.; 3. Final reductions of 37 per cent, 50 per cent, 69 per cent and 84 per cent;

Jan 1, 1942

By C. A. Komar

Renewed interest in the underground gasification of coal evolves from comprehensive studies of earth fracture systems that indicate that the movement of fluids can be controlled in the coalbed. In particular, directional property studies of natural microfissure occurrence, permeability, ultrasonic velocity, tensile strength, and orientation of intervals of inherent rock weakness, together with geologic structure setting and fracture trace analysis, can predict the gaseous flow paths in the coalbed. Having this information, the dominant direction in which gases generated and/or liberated by heat would move can be determined so that appropriate well patterns can be developed. Together with advances made in drilling technology that permit long horizontal holes to be drilled through the coal seams, tests can be conducted to determine whether directional control will permit devolatilization of the coalbed and gasification of the remaining hot coke in a systematic manner to produce a low-Btu gas suited for the generation of electricity.

Jan 1, 1973

By G. J. Abbaschian, A. B. Gokhale, M. M. Kunjapur

"A laboratory scale model furnace was constructed for obtaining radially inward oriented columnar grains in disc shaped castings. The furnace consisted of eleven circular, concentric, equispaced resistance heaters on each half of a split graphite mold. Water or air flowing through a copper pipe along the periphery of the disc constituted the heat sink. After filling the mold, the heaters were turned off consecutively in top and bottom pairs from the rim towards the center, causing the temperature gradients to move inward. Equiaxed structure was obtained at the center by turning off the inner coils together when desired. Sn:15%Pb alloy was used to cast integral blade disc castings using the above technique to obtain dual-property discs with a central equiaxed structure and an outer columnar grain structure projecting inwards from the blades to the rim. A numerical technique was used to predict the temperature profile in the disc during solidification, and good correlation was obtained with the experimentally measured temperature profiles. The corresponding heat transfer coefficient values obtained were h = 544 Wm- 2k-1 (0.013 cal/cm2- ° C-sec) for cooling between metal and chill and h' = 71 Wm- 2k-1 (0.0017 cal/cm2- ° C-sec) for the heat input from the hot mold to the liquid metal. BackgroundHigh temperature alloys used in the current generation of gas turbine engines have evolved through two main stages of development: in 1950's, the increase in the efficiency of gas turbines was paced by improvements in alloy design, which led to the development of Ni and Co-based superalloys (1). By mid-1960's, it was realized that improved alloy chemistry alone was inadequate in meeting the increasingly stringent service requirements. The focus of research then shifted from alloy development to process development, and resulted in the introduction of directional solidification (DS) techniques for the production of turbine blades and vanes (1,2).Under typical operating conditions, the blades and vanes are subjected to aerodynamic loading, while the blades are additionally subjected to high centrifugal loading and vibratory stresses. The primary material requirements for blades may be summarized as follows (1,3):•,High creep resistance•,Good high temperature tensile strength (typically in the range of•,275 to 550 MPa at temperatures in excess of 750°C)•,Resistance to both low cycle and high cycle fatigue (LCF and HCF)•,Resistance to erosion, corrosion, and oxidation•,Resistance to thermal fatigue"

Jan 1, 1986

Reduce dust at the auger mine face by modifying airflow patterns, around the minim machine. Approach Limited clearance between an auger miner and the mine root restricts airflow across the face and causes dust rollback. Directional sprays arc used to direct air across the face, thereby reducing dust rollback and increasing dust dilution (fig. 1). Laboratory and underground studies were used to test and optimize effectiveness of the directional sprays. Results of Laboratory Study Laboratory experiments were conducted in a simulated auger gallery equipped with a full-scale mock auger miner and bridge conveyor. A dual curtain configuration was used to direct the, ventilation, which averaged 2,700 cfm throughout the experiment. Testing variables included spray location, pressure, spacing, orientation, and number. Figure 2 shows the optimized directional spray system, also called the auger clearer spray system. The system consists of three sprays mounted alone the intake side of the miner. Sprays arc spaced 16 to 24 inches apart, and angled 30° toward the return side of the miner. The 24-inch spacing moved about 7% more air across the face than the 16-inch spacing; however, it resulted in some additional misting on the return side of the miner. A 30° orientation was more effective than a 60° orientation for moving air across the face and minimizing misting on the return side of the miner. Flat fan sprays arc used because their spray paths arc not obstructed by the top of the miner and mine roof, A 50° fan angle is used to minimize misting on the intake side of the miner.

Jan 1, 1989

By Spencer R. Titley

Nearly three decades of intense research, corresponding with a period of unparalleled discovery and the advent of scientific advances and hypotheses of ore formation, has resulted in a great body process-focused research concerning how ore deposits form. The development of process models and their application has proceeded more or less in step. Discoveries have been made in mineralized regions such as provinces and districts but generally without a comparably developed understanding of why provinces and ore bodies exist and, except in general terms, where ore deposits are within districts and regions. The process of discovery is still referred to as search and exploration budgets are heavily weighted toward exploration drilling.

Jan 1, 1995

By Gary Nash

While there could be as many directions on regulations as there are viewpoints surrounding the asbestos controversy, there are a few basic criteria that generally will influence government thinking, namely: - their definition of the problem to be regulated, - their interpretation of the scientific evidence available to them, and - their sensitivities to the views of, and the implications for, various interest groups in society. Clearly, different assessments of these criteria by various governments will lead to differing regulatory regimes. The consequence, of course, is a patchwork of non-conforming regulations among nations, with all that thin implies for the distortion of international trade and the unsettling of international relations. I would therefore argue that when governments are examining regulatory action, they should explicitly take into account their common interests in stable and cordial international relations, and when possible, efforts should be made to ensure that movement on regulation is at least, in principle, in accord with the general views of the international community.

Jan 1, 1984

? Élaboration de la Directive 019 (1982) ? Objectifs: ? Protection de l ?environnement ? Procédure administrative pour analyse et évaluation environnementale ? Officialisée en 1989 ? pas eu de modifications depuis ce temps Contenu de la Directive 019 ? Requête d ?autorisation ? Gestion des eaux ? Traitement des effluents ? Gestion des déchets et des résidus miniers ? Suivi environnemental Directive 019 Exigences environnementales ? Effluents miniers ? As, Cu, Ni, Pb, Zn, Fe, CN, MES, pH, toxicité aiguë ? Suivi environnemental annuel ? Effluent ? Réseau hydrographique ? Restauration

May 1, 2001

L50 Adirondack L1 Alaska L2 Arizona L58 Arkansas L66 Billings Petroleum L3 Black Hills L4 Boston L5 Carlsbad Potash L6 Central Appalachian L60 Central New Mexico L7 Chicago L8 Cleveland L9 Colorado L57 Colorado Plateau L10 Columbia LII Connecticut L55 Dallas L12 Delta L65 Denver Petroleum L13 Detroit L14 East Texas L15 El Paso Metals L71 Evangeline L45 Florida L54 Fort Worth L16 Gulf Coast L61 Hobbs L62 Hugoton L68 Illinois Pet Basin L17 Kansas L18 Lehigh Valley L52 Lou-Ark L47 Mexico L19 Mid-Continent L20 Minnesota L56 Mississippi L21 Montana L22 Nevada L64 Niagara Frontier L23 New York L67 New York Petroleum L25 North Pacific L24 North Texas L26 Ohio Valley L27 Oklahoma City L28 Oregon L63 Panhandle L29 Penn -Anthracite L30 Permian Basin L51 Peru L31 Philadelphia L32 Pittsburgh L33 St Louis L34 San Francisco L59 San Joaquin L35 Southeast L36 Southern Calif L69 Southern Calif Pet L53 South Plains L37 Southwest Texas L48 Southwest Alaska L38 Southwest N Mex L44 Spindletop L39 Tri-State L40 Upper Peninsula L41 Utah L70 Venezuela L42 Washington, D C L43 Wyoming L49 West Central Texas L46 Philippine

Jan 1, 1956

By Richard L. Sanford

This paper summarizes the results of the development of a Directory of Computer Programs Applicable to U.S. Mining Practices and Problems. The Directory is funded by the U.S. Bureau of Mines and includes a sampling of computer usage in operating and manufacturing companies, consulting firms, computer companies, research organizations, universities, and various U.S. government agencies. General references to computer applications throughout the mining industry are discussed as well as the availability of programs to interested organizations or individuals.

Jan 1, 1978